This is an undocumented API used by some programs to fetch the user's selected languages.
Example is Fusion360 (during its login process).
Signature currently taken from here: https://stackoverflow.com/questions/63877075/what-is-the-right-way-to-get-th... (Maybe that stackoverflow answer is also why Fusion has implemented this...) And I haven't found a way yet to retrieve a result that is not static.
-- v9: bcp47langs: Implement GetUserLanguages