[For now no patch, please dont apply it, it's only a previous patch as placeholder due to phabricator needs a patch to open new diff, but I only open diff here because I don't get to address people in trac (#4911) correctly, so asking here before I actualy implement this feature so patch is not correctly here and missing.]
So discussion:
For changing language in lobby or in gamesetup or in-game it can be good to have language changing possibility within the options window (when options window become globaly or also in lobby/gamesetup available) f.e. if want to change from native language like german to english, when ingame or in gamesetup, for looking up proper english name for a map or unit to talk to others in english, but then switch back to native language (german), this can be really helpful. Interest?