That's more than a detail. It's a game-changer and a very big deal. France has its own braille authority and its own rules. If you have determined that following the Interim Manual is not appropriate, I'm afraid you can't pick and choose. French braille now uses Antoine numbers AND uses composition signs differently along with different font attributes. And French is contracted. For all these reasons, that puts it beyond the scope of this forum and beyond the scope of NBA. We can only advise interpretation and application of BANA rules and BANA is the Braille Authority of North Amerioca only.
However, if you feel that using the Interim Manual would work even in this situation, let us know if we can be of any help.