Gets contextual culture server validation working

src/Umbraco.Web.UI/Umbraco/config/lang/en_us.xml

@@ -2063,6 +2063,9 @@ To manage your website, simply open the Umbraco back office and start adding con
         <key alias="invalidDate">Invalid date</key>
         <key alias="invalidNumber">Not a number</key>
         <key alias="invalidEmail">Invalid email</key>
+        <key alias="invalidNull">Value cannot be null</key>
+        <key alias="invalidEmpty">Value cannot be empty</key>
+        <key alias="invalidPattern">Value is invalid, it does not match the correct pattern</key>
     </area>
     <area alias="healthcheck">
         <!-- The following keys get these tokens passed in: