Got models pulled apart and simplified, much less inheritance and easier to follow, start wiring up the model binding logic for content along with validation for each variant

src/Umbraco.Web/Models/Mapping/ResolutionContextExtensions.cs

@@ -0,0 +1,28 @@
+using AutoMapper;
+
+namespace Umbraco.Web.Models.Mapping
+{
+    /// <summary>
+    /// Extension methods for AutoMapper's <see cref="ResolutionContext"/>
+    /// </summary>
+    internal static class ResolutionContextExtensions
+    {
+        public const string CultureKey = "ContextMapper.Culture";
+        
+        /// <summary>
+        /// Returns the language Id in the mapping context if one is found
+        /// </summary>
+        /// <param name="resolutionContext"></param>
+        /// <returns></returns>
+        public static string GetCulture(this ResolutionContext resolutionContext)
+        {
+            if (!resolutionContext.Options.Items.TryGetValue(CultureKey, out var obj)) return null;
+
+            if (obj is string s)
+                return s;
+
+            return null;
+        }
+    }
+}
+