Pretty sure AC will check through on separate tickets, as long as the agent at check in is willing to put up the effort needed and possibly the effort needed to find out how to do it. AC has no policy against checking through on separate tickets, in contrast with One World airlines. As long as they interline, and definitively if both are Star Alliance. We have done this a few times, last one being YYC-YVR-ICN on AC and then ICN-Kunming on a Chinese airline that's a member of the AF/Delta/Korean alliance. Once on AC to SYD and then NZ. Once AC to LHR and then LH to somewhere in Germany. OTOH, true that it's a good idea to plan for a long connection, in case the first flight is delayed long enough to miss the second flight.