Brice it's a bit of a minefield...I had the ppl flight training and test in France around six years ago for the initial issue of a ppl...theory was based on my UK ATPL...took a lot of comms and eventually all ...including my Frog medicals..accepted..as was my renewal until this year which is where it got complicated.
Two months ago I enquired whether the same club and ex airfrance examiner were still acceptable...as is the French class 2... Got various links (including a 888 page document) and a complicated answer back...and told that I need an english test.....jaa "testicles" IMHO...so have given up and am considering obtaining a French license.
But suggest a call to the CAA for your friend might be more productive...which is how I eventually sorted out my initial PPl issue.