I’d be very wary of taking the French Government to court, as its only going to end one way and probably not the way you want it. A lot of time, money and heartache will be involved and potentially for nothing.
The French are very nationalistic and will never do anything that would undermine that.
If you work in that country you need to play by their rules. If they say you need qualification X to operate, then thats what you need. Yes you may think that the qualifications are similar, but if the French dont then it doesnt matter.
Same with any other qualification, Doctor, Nurse, Lawyer. You may be a fully UK qualifed Doctor with 10 years experience then you would still have to undertake the French equivalent before you could practice.
Sounds like you’re taking the legal position of making all qualifications transferable across Europe, and the only way your going to do that is via the European court and unless you have a huge amount of time and money isnt going to happen.
Good luck with it, but i feel you’d be better concentrating your efforts of gaining the relevant qualification for the market you want to operate in.