diff --git a/Models/ThemeConfig/Conversion/Conversion.ts b/Models/ThemeConfig/Conversion/Conversion.ts
index 6d93c0158d..da5cca313a 100644
--- a/Models/ThemeConfig/Conversion/Conversion.ts
+++ b/Models/ThemeConfig/Conversion/Conversion.ts
@@ -19,14 +19,17 @@ export abstract class Conversion<TIn, TOut> {
     }
 
     public static strict<T>(fixed: { errors?: string[], warnings?: string[], information?: string[], result?: T }): T {
-        if (fixed?.errors !== undefined &&  fixed?.errors?.length > 0) {
-            throw fixed.errors.join("\n\n");
-        }
+       
         fixed.information?.forEach(i => console.log("    ", i))
         const yellow = (s) => "\x1b[33m"+s+"\x1b[0m"
         const red = s => '\x1b[31m'+s+'\x1b[0m'
-        
         fixed.warnings?.forEach(w => console.warn(red(`<!> `), yellow (w)))
+
+        if (fixed?.errors !== undefined &&  fixed?.errors?.length > 0) {
+            fixed.errors?.forEach(e => console.error(red(`ERR `+e)))
+            throw "Detected one or more errors, stopping now"
+        }
+        
         return fixed.result;
     }
 
diff --git a/Models/ThemeConfig/Conversion/Validation.ts b/Models/ThemeConfig/Conversion/Validation.ts
index 46d426793b..c5afde99f7 100644
--- a/Models/ThemeConfig/Conversion/Validation.ts
+++ b/Models/ThemeConfig/Conversion/Validation.ts
@@ -238,8 +238,25 @@ export class PrevalidateTheme extends Fuse<LayoutConfigJson> {
 }
 
 export class DetectShadowedMappings extends DesugaringStep<TagRenderingConfigJson> {
-    constructor() {
+    private readonly _calculatedTagNames: string[];
+    constructor(layerConfig?: LayerConfigJson) {
         super("Checks that the mappings don't shadow each other", [], "DetectShadowedMappings");
+        this._calculatedTagNames = DetectShadowedMappings.extractCalculatedTagNames(layerConfig);
+    }
+
+    /**
+     * 
+     * DetectShadowedMappings.extractCalculatedTagNames({calculatedTags: ["_abc:=js()"]}) // => ["_abc"]
+     * DetectShadowedMappings.extractCalculatedTagNames({calculatedTags: ["_abc=js()"]}) // => ["_abc"]
+     */
+    private static extractCalculatedTagNames(layerConfig?: LayerConfigJson){
+        return layerConfig?.calculatedTags?.map(ct => {
+            if(ct.indexOf(':=') >= 0){
+                return ct.split(':=')[0]
+            }
+            return ct.split("=")[0]
+        }) ?? []
+        
     }
 
     convert(json: TagRenderingConfigJson, context: string): { result: TagRenderingConfigJson; errors?: string[]; warnings?: string[] } {
@@ -248,6 +265,10 @@ export class DetectShadowedMappings extends DesugaringStep<TagRenderingConfigJso
         if (json.mappings === undefined || json.mappings.length === 0) {
             return {result: json}
         }
+        const defaultProperties = {}
+        for (const calculatedTagName of this._calculatedTagNames) {
+            defaultProperties[calculatedTagName] = "some_calculated_tag_value_for_"+calculatedTagName
+        }
         const parsedConditions = json.mappings.map(m => {
             const ifTags = TagUtils.Tag(m.if);
             if(m.hideInAnswer !== undefined && m.hideInAnswer !== false && m.hideInAnswer !== true){
@@ -263,7 +284,7 @@ export class DetectShadowedMappings extends DesugaringStep<TagRenderingConfigJso
                 // Yes, it might be shadowed, but running this check is to difficult right now
                 continue
             }
-            const keyValues = parsedConditions[i].asChange({});
+            const keyValues = parsedConditions[i].asChange(defaultProperties);
             const properties = {}
             keyValues.forEach(({k, v}) => {
                 properties[k] = v
@@ -289,10 +310,6 @@ export class DetectShadowedMappings extends DesugaringStep<TagRenderingConfigJso
 
         }
 
-        // TODO make this errors again
-        warnings.push(...errors)
-        errors.splice(0, errors.length)
-
         return {
             errors,
             warnings,
@@ -341,9 +358,9 @@ export class DetectMappingsWithImages extends DesugaringStep<TagRenderingConfigJ
 }
 
 export class ValidateTagRenderings extends Fuse<TagRenderingConfigJson> {
-    constructor() {
+    constructor(layerConfig: LayerConfigJson) {
         super("Various validation on tagRenderingConfigs",
-            new DetectShadowedMappings(),
+            new DetectShadowedMappings( layerConfig),
             new DetectMappingsWithImages()    
         );
     }
@@ -439,7 +456,7 @@ export class ValidateLayer extends DesugaringStep<LayerConfigJson> {
                 }
             }
             if (json.tagRenderings !== undefined) {
-               const r = new OnEvery("tagRenderings", new ValidateTagRenderings()).convert(json, context)
+               const r = new OnEvery("tagRenderings", new ValidateTagRenderings(json)).convert(json, context)
                 warnings.push(...(r.warnings??[]))
                 errors.push(...(r.errors??[]))
                 information.push(...(r.information??[]))
diff --git a/assets/themes/grb_import/grb_fixme.json b/assets/themes/grb_import/grb_fixme.json
index 2ae057dfd4..f86e294e8b 100644
--- a/assets/themes/grb_import/grb_fixme.json
+++ b/assets/themes/grb_import/grb_fixme.json
@@ -127,16 +127,12 @@
             },
             {
               "if": "building=apartments",
-              "then": "An apartment building - highrise for living"
+              "then": "An apartment building (a highrise building for living)"
             },
             {
               "if": "building=office",
               "then": "An office building - highrise for work"
             },
-            {
-              "if": "building=apartments",
-              "then": "An apartment building"
-            },
             {
               "if": "building=shed",
               "then": "A small shed, e.g. in a garden"
diff --git a/assets/themes/uk_addresses/uk_addresses.json b/assets/themes/uk_addresses/uk_addresses.json
index 4a46793bf1..e09a24ae05 100644
--- a/assets/themes/uk_addresses/uk_addresses.json
+++ b/assets/themes/uk_addresses/uk_addresses.json
@@ -256,13 +256,14 @@
           },
           "mappings": [
             {
-              "if": "addr:unit=",
-              "then": "<div class='subtle'>Sub-unit (e.g. \"1\", \"Flat 2\", \"Unit C\")</div>",
-              "hideInAnswer": true
+              "if": "not:addr:unit=yes",
+              "then": "There is no sub-unit within this address",
+              "addExtraTags": ["addr:unit="]
             },
             {
               "if": "addr:unit=",
-              "then": "There is no sub-unit within this address"
+              "then": "<div class='subtle'>Sub-unit (e.g. \"1\", \"Flat 2\", \"Unit C\")</div>",
+              "hideInAnswer": true
             }
           ],
           "condition": {
@@ -291,17 +292,12 @@
                   "addr:housename="
                 ]
               },
-              "then": "<div class='subtle'>House or building name</div>",
-              "hideInAnswer": true
+              "then": "This building has no housename"
             },
             {
-              "if": {
-                "and": [
-                  "nohousename=yes",
-                  "addr:housename="
-                ]
-              },
-              "then": "This building has no housename"
+              "if": "addr:housename=",
+              "then": "<div class='subtle'>House or building name</div>",
+              "hideInAnswer": true
             },
             {
               "#": "By adding nohousenumber!=yes, this option will trigger when first added, but will be untriggered if a housenumber is added, resulting in the question poping up!",
@@ -329,10 +325,18 @@
             ]
           },
           "mappings": [
+            {
+              "if": "nohousenumber=yes",
+              "then": {
+                "en": "This building has no house number",
+                "nl": "Dit gebouw heeft geen huisnummer",
+                "de": "Dieses Gebäude hat keine Hausnummer"
+              },
+              "addExtraTags": [ "addr:housenumber="]
+            },
             {
               "if": {
                 "and": [
-                  "nohousenumber=yes",
                   "addr:housenumber="
                 ]
               },
@@ -340,19 +344,6 @@
                 "en": "<div class='subtle'>Number (e.g. 1, 1A, 2)</div>"
               },
               "hideInAnswer": true
-            },
-            {
-              "if": {
-                "and": [
-                  "nohousenumber=yes",
-                  "addr:housenumber="
-                ]
-              },
-              "then": {
-                "en": "This building has no house number",
-                "nl": "Dit gebouw heeft geen huisnummer",
-                "de": "Dieses Gebäude hat keine Hausnummer"
-              }
             }
           ]
         },
@@ -373,17 +364,17 @@
           },
           "mappings": [
             {
+              "if": "not:addr:substreet=yes",
+              "then": {
+                "en": "No extra place name is given or needed"
+              },
+              "addExtraTags": ["addr:substreet="]
+            },{
               "if": "addr:substreet=",
               "then": {
                 "en": "<div class='subtle'>Place (e.g. \"Castle Mews\", \"West Business Park\")</div>"
               },
               "hideInAnswer": true
-            },
-            {
-              "if": "addr:substreet=",
-              "then": {
-                "en": "No extra place name is given or needed"
-              }
             }
           ],
           "condition": "addr:parentstreet="
@@ -403,18 +394,19 @@
             ]
           },
           "mappings": [
+            {
+              "if": "not:addr:substreet=yes",
+              "then": {
+                "en": "No extra place name is given or needed"
+              },
+              "addExtraTags": ["addr:substreet="]
+            },
             {
               "if": "addr:substreet=",
               "then": {
                 "en": "<div class='subtle'>Place (e.g. \"Castle Mews\", \"West Business Park\")</div>"
               },
               "hideInAnswer": true
-            },
-            {
-              "if": "addr:substreet=",
-              "then": {
-                "en": "No extra place name is given or needed"
-              }
             }
           ],
           "condition": {
@@ -479,15 +471,9 @@
           },
           "mappings": [
             {
-              "if": "addr:parentstreet=",
-              "then": {
-                "en": "<div class='subtle'>Parent street name</div>"
-              },
-              "hideInAnswer": true
-            },
-            {
-              "if": "addr:parentstreet=",
-              "then": "No parent street name is needed within this address"
+              "if": "not:addr:parentstreet=yes",
+              "then": "No parent street name is needed within this address",
+              "addExtraTags": ["addr:parentstreet="]
             },
             {
               "if": "addr:parentstreet:={_closest_street:0:name}",
@@ -503,6 +489,13 @@
               "if": "addr:parentstreet:={_closest_street:2:name}",
               "then": "<b>{_closest_street:2:name}</b>",
               "hideInAnswer": "_closest_street:2:name="
+            },
+            {
+              "if": "addr:parentstreet=",
+              "then": {
+                "en": "<div class='subtle'>Parent street name</div>"
+              },
+              "hideInAnswer": true
             }
           ],
           "condition": {