And last, but not least, In CDG we speak french because we are in our country. Check what annex 10 of ICAO says !!! it will be the same in MAD, FCO, etc...
Speak 3 languages, work in Italy, still doing ATC and briefings in english, which is not my own language, reply to clearances in italian in english...all this just because of safety.
If this is not a subject for AF or the frensh pilots.....well go ahead, we have already seen where this leads to.
Flew with some french guys, 2 french crewmembers and 2 non french in the cockpit, the french guys were always talking in french even about flight related things. Very good CRM....the french way
BTW: it was not a french company we were flying for, not even in France.