At a recent conference in London we were briefed that Agil Azur has decided its pilots will all speak English to ATC over France. Good news.
On of the CDG managers talked to the Eurocontrol Safety Forum in June and said that the use of French by ATC/Francophone pilots at CDG was now recognized as a hazard and was on the risk register. The main problem (apparently) is that not all the ground handlers speak English. Why that means all the other locals should speak French is entirely another matter.