I am experimenting with adding a new language (Azerbaijani) to LT (using procedure on Adding A New Language - LanguageTool Wiki). So far, I have been able to get it working with Hunspell rules on standalone application. However, the new language does not show up when I connect the Firefox add-on to local server. Is there something I have missed?
The languages in the add-on are hard-coded. A hack would be to replace some other language with yours and use that one, until Azerbaijani is added to the add-on (once it has stabilized). In other words, just pretend your language is, say, Esperanto in the Java code and then select Esperanto in the add-on.
I’ve just got the same problem, we have GET /v2/languages API, should not we use this to get the list?
Replacing another language is quite a hack and does not scale well for multiple users.