EPM language for Yealink and Grandstream phones

We use Yealink and Gradstream’s phone in an apartment house in which we have guests with different languages (standard languages). In the extension module I can set the language.

But in EPM isn’t any option and in basefiles I could set phone’s display language “hardcoded” only. Unfortunately there isn’t any variable with extensions language code. Also unfortunately phones have different values for languages eg. Yealink uses “German” while Grandstream uses “de”.

One solution could be that FreePBX provides two variables one with language short code (“en”) and one with language description like “English” or “German”. The correct variable can be used in phones basefile.

What do you think? Thank you.