The course being in French will be by far the biggest issue.
I know pilots elsewhere in Europe who I know are very good English speakers, but they mostly still prefer to do the ATPL exams in their own language.
As regards flying within France, once you go away from "international" airports then you are supposed to speak the native language - in any country.
I guess the language issue has been raised in the context of non-Frenchmen doing the French IR. The problem is that you will then have a French issued PPL and (regardless of how you obtained that without living there) you will be stuck with it in your home country, where questions are perhaps more likely to be raised. Presumably one would immediately convert it back?
The really interesting aspect of the French IR is that, IIRC, they will hand it out to anybody with an FAA IR.
If they don't do that, and e.g. require zero training but still make you sit all the exams and pass a flight test (which is what the CBM IR is, currently) the package is far less attractive because the amount of flying which you are going to need to pass a JAA IR test anywhere in N Europe is likely to be way above the minimum 15hrs ICAO IR to JAA IR conversion requirement.
By the time one gets down to the details, and looks at the actual differences, and crucially realises that the existence of the present JAA IR QB (in various online forms) reduces the exam revision by a factor of about 10x, the offer on the table right now is probably as near as dammit to anything we will ever get in the future.
The detail will be interesting...