There are some things to mention when localizing moregroupware. These problems will not remain for years, but at the moment, you must watch out for the following:
your first module translation should be "settings". Because when you add a new language and you translate only a module like calendar, moregroupware will fail in the same second when you switch your personal language to the new one. This is because the switching itself occurs in the module "settings" and before you have the chance to change to your translated module, moregroupware will search for a translation of "settings".