I decided on a simpler method of combining French and Japanese conjucations. I already implemented the method of having French negation for French words, and Japanese negation for Japanese loan words.
I think I may take this a step further, and have the user either use French conjucations and prepositions for French words, and then Japanese conjucation so that there isn't as much confusion when words are used.
Ex. Mata for Tsunami, Ou for Baguette.