The mods of the community may only have chosen Undetermined for the allowed languages for simplicity purpose, and some third-party apps don’t let you choose a language when posting so you can’t really turn that one off either without breaking something at the moment.
Also if each user don’t have the language you’ve posted in their preferences (most only have Undetermined selected) they will not see your post since it will be filtered out.
Perhaps we can have all Languages selected by default and let the user remove them later. That way, you won’t be missing anything you don’t know you are missing.