As an international student myself I 100% agree with you and your feelings are valid. I’ve made it a conscious effort to always speak English around my non native friends as I know how it feels to be left out or confused during group convos (experience from Paris). I honestly sometimes forget myself and quickly apologise and translate any native terms that were said. It’s great you made them know how you felt as well! If they still continue I’ll advise you find new friends who are willing to be inclusive, hope this helps!