https://www.camptekakwitha.ca/
Camp is in Maine but operated by Canadians, 60-70% percent of the campers are Canadian, mostly from Montreal and Quebec. Remaining campers are mostly from cities in the U.S. Flights from WAS to Portland, Maine and shuttle service to/from airport if you want/need it.
This is not a fancy camp but if your teen speaks at an intermediate or above level of french and likes to hike (14-16 years go camping and hiking on Appalachian trail from 7-16 days) this might be an option worth considering.