Preferences -> Environment -> Interface -> Language - how do I add languages?

[Navadvipa Chandra das]

Hello, All!

I compile Qt and QtCreator from the source texts and now I want add languages for user interface QtCreator:

Preferences -> Environment -> Interface -> Language - how do I add languages?

Now there are only two points:
<System languages>
English

But in fact, any of them gives English.

Thanks!

With best regards, Navadvipa Chandra das.