Indeed, as EY is entirely outside Skyteam, and is not a Flying Blue partner, there is absolutely no question of AF elites having access to lounges when travelling on AF-coded EY-operated flights.
There may be one or two places where there is some other agreement in place - I don't know, but perhaps AF elites travelling on AF-coded flights from CDG have access to the Etihad lounge - but you should never expect your Flying Blue status to get you into a non-Skyteam lounge, except in those cases where an exceptional agreement is in place.