How to implement language translations on App Extensions?

Summary: In fusion, there is an option to change the language in set preferences, change the language in session settings to test language packs. How to pass the value to App extension to call the related strings in translation bundle?

Content (required): In fusion, there is an option to change the language in set preferences, and change the language in session settings to test language packs. How to pass the value to App extension to call the related strings in the translation bundle? I referred to below documentation hyperlink and I am not understanding how does the fusion user selection is passed to App extension