Really, there is no need for people to get hot under the collar about this. Despite rumours to the contrary, France is not a centralised country.
All the above contributors are both right, and wrong.
It depends where you live. Not only does every prefecture have a different idea of the rules but all of the foncs within it have different ideas also.
So, everybody has a different experience, nobody is right or wrong.
Mine was this. I wasn’t allowed to drive an HGV until I had exchanged my UK licence for a French one.
That took one day at the sous-prefecture (probably prefecture only now).
My boss then set me to work and forgot to mention FCOS and, as I had never heard of it, rolled on blithely without it.
Then, in a minstry check it was discovered and I was told to tell the boss to do something about it. He did, immediately, and I did the 3 day course with 3 other drivers from the firm.
There was no such thing as a driver CPC in those days so the matter of acceptance or otherwise did not apply.
Someone mentioned having to do FIMO even though having 25 years experience. FIMO is for newbies, drivers with less than 10 years, thus I didn’t have to do that.
So you see, it simply matters where you live to determoine what you have to do, or not.
BTW, nice to see you are still plodding on Craig, I keep looking for you whenever I see a STEF Premium. My mount nowadays is a grey Berlingo with a white Eriba caravan and am still doing 70,000 kms/year delivering the dogs.