From the FP T&C's (bolding mine):
- Flight credits can be used only for flights operated by Air Canada, Air Canada rouge and Air Canada Express carriers (Jazz, Sky Regional, Air Georgian and Exploits Valley Air Services (EVAS)). Codeshare flights are not permitted. You may want to learn more about Air Canada rouge's and/or Air Canada Express's flight services and amenities, as these differ from those of Air Canada.