Font files themselves cannot specify languages. Rather, the game calculates the hash of the first font (usually font01.vf) and sets the language based on that. However, this only works for English, German, and Polish (because FS2 was never actually released in French), and it doesn't work with custom-made fonts (because they would have different hashes). Of course, if a language is specified in the registry, then that is used instead.
I'm pretty sure that Novachen meant to suggest that you delete the Language value, not the whole Freespace2 key! Since you did that, you need to start the game, close it, then check the registry to ensure that the Freespace2 key has been recreated. If it has, then add a string value (highlight the Freespace2 key, then in an empty part of the area that has things like LastPlayer and SoundDeviceOAL, right-click -> New -> String Value, assuming it's in English) and name it Language
. Then, set its data to French
(you might need the capital F).
You can find it in HKEY_LOCAL_MACHINE\SOFTWARE\WOW6432\Volition\FreeSpace2 on x64 systems. On 32-Bit it should be the same without the WOW6432 key.Nope. The real location is found on this page, in the "Registry" section: http://www.hard-light.net/wiki/index.php/Getting_started_with_FreeSpace_2#Registry
Thats interesting, because i did not have this one on Win10.
Oh, right, that's another location where the settings can be stored (except WOW6432 is really Wow6432Node). I'll add it to the wiki shortly. EDIT: Done!