I was able to add Italian Language and it seems to work correctly:
- open localelanguages table
- find your language and set the "Usage" column to 1
- go in AM
- open "Resource Bundle" and select "Files" folder
- then select "ALL" as "Resource Bundle" and "GENERATE"
- now you have to add your new language in the "Language Library" in AM
- naturally you have to translate all in you language if not already so...