You can create a specific file(s) so that the form is in French but the fill in field where the data comes from Adagio will be in English though.

In AR & AP you can enter specific customer and vendor names & addresses in French.

Not perfect by any means but your client's customers will appreciate the effort. I believe the Quebec's French language laws still allow English for technology and with few exceptions amongst that older generations, everyone speaks and reads both English and French.