My in-laws and husband all said what I would have told you: you'll need to contact the schools individually and find out how they want you to present your information. It is not uncommon for American schools to have very little knowledge of education systems that are different from their own. You might also try getting in contact with the school's foreign language department. There may be a French prof there who is familiar with the French system (not all are) and can talk to the admissions office on your behalf. Even if they don't have someone with that knowledge they may know of a prof in another department who is from France and could help. My mother-in-law, who is French, ran into a similar issue when applying to grad school here. She was able to find a French prof at the school who explained to the admissions board that her GPA of 12/20 was actually very good. Let me know if I can be of any further assistance. Bonne chance!