this does not address the main problem that flags do not correspond to languages. German is spoken in more than "the three" countries, and in these countries there are more languages than German. Thus, using flags is insensitive and alienating to German speakers from other countries (e.g., Belgium), and non-German speakers from these three countries (e.g., Lugano).
And this is just for German! The situation is even more complicated for nearly all other languages in the world. Please, never use flags of states to identify languages. I have been on the receiving end of this unnecessarily offensive thing, and it did not feel nice.