Yeah, the ExternalKeyboard plugin doesn't handle custom keymaps, so it sort of assumes a standard PC105 IBM QWERTY layout. Patches welcome.
I don't actually remember what exactly happens with an AZERTY keyboard (i.e., whether it behaved as if QWERTY, or if something weirder happened).
Not for the faint of heart to deal with, though. (IIRC, ideally, the plan would have been to be able to piggyback on standard Linux console layout or xkb stuff).
My own interest stopped at getting it technically working, though

.