I've come across French players who actively refuse to speak any English especially when they have someone who isn't native speaker and if you ask to do so start to behave in a negative manner. Reverting to English is something everyone should be capable of as should common courtesy. But I have found many choose not too and that's a sad thing and pisses me off if I am honest.

Generally I have F not highlighted in my duties etc but if I come across them if they are nice and play well thats fine - but as OP noted when its 3 of them and 1 of you - its not a nice experience. But the French overall have a bad reputation in games I have found - and people are especially vocal about it on my server. But everyone's experience is different. Don't let it get to you just hold your head high and move on. Hopefully you don't have to go through that situation again.

SE could maybe perhaps do like WoW did and have servers for different countries. But that's not likely tbh..