I take OP's complaint that it is a Rouge plane to mean not that the legal ownership is Rouge (which is typically irrelevant to the passenger), but that it is a plane configured for and befitting Rouge. (That's consistent with your point, not an objection to it.) It's a bit like if AC advertised Porsche service for J passengers and then a Lada showed up, Lada having recently been acquired by Porsche (or say *that* Lada having recently been acquired by Porsche). Sure, it's a Porsche car that showed up, but nonetheless it's not the service advertised.

I don't know in Canada what counts as an unacceptable service swap for airlines. There was that New Zealand case recently where someone successfully sued Emirates because their flight was marketed to make it sound like they'd get the luxury lie flat seats but they got the boring old angle flat seats. There's obviously some limit to what's an acceptable swap, e.g. if I book a 787-9 AC couldn't swap in a WWII era open cockpit fighter plane (as cool as that would be). But I have no idea if the boundary has been defined in law (most likely by a court if at all).

AC does need to do a better job of making marketing materials accurate. I constantly see international Flex highlighted as having free changes when I search for flights using the app, even though there is a change fee. This seems crazy to me, I mean how was that not fixed immediately after someone noticed it? As for OP, I don't know whether AC advertises Y as having a minimum seat pitch but they do announce North American Y has seat back entertainment: https://www.aircanada.com/ca/en/aco/...y-class.html#/ Arguably just buying a Rouge plane and flying mainline routes with it is part of a pattern of contempt or at least disregard for passengers, the same sort of culture that lets an airline be content to not fix misadvertising flex international and other things well-documented on FT.