Regarding language extensions - the information in the extension (language name and font mapping) is only read when the campaign is first created. So you have to remember to include the extension when you first create the campaign. If you add the extension after the campaign has been created, then you won't see the language names added to the language list, but you will have the new fonts available so you can manually create what you need).
A work around, is mentioned in the first post here:
https://www.fantasygrounds.com/forum...s-(FG-v3-1-3-)