In your original post you said that all EV routes in France were part of the French national scheme. Which brings us to a potential problem with routes that belong to two networks (EV and national)

My question “are there any parts of EVs in France that do not belong to a national route” aims at discarding the above issue: if there is both an icn relation and a nwn relation in OSM, then each of these belong to exactly one network (EV or national)