As far as I can tell all the filecards from 1982-1994 were English/French, even the mail-away 1982 & 1984 Cobra Commander, 1984 Duke, Steel Brigade figures, six-driver figure set and the Original team 10 figure set.
I don't know whether Starduster, Ninja Vipers or any 90's mail-away got an English/French filecard (I've never paid close attention to them, though).
However, I do know that sometimes you could get US packaged items on the shelves (Toys R Us mostly) and thats where some confusion might be taking place.