Actually, they are trying to add multiple languages in the <TargetLanguage> element. It doesn't appear this allows a list of language codes based on the applicability schema:
https://msdn.microsoft.com/en-us/library/windows/desktop/bb972753(v=vs.85).aspx The target language should likely look something like this: <TargetLanguage Validate="false">0</TargetLanguage>
There's is currently: <TargetLanguage Validate="false">0,1033,1030,1043,2057,1035,1036,1031,1040,1041,1042,1044,1034,1053</TargetLanguage>
I would recommend that you reach out to them directly since you are licensed and likely have support.