I'm skeptical this is going to work out like you wish, but I'll keep fingers crossed for you.

In KHN, they technically should be able to interline and tag through if they know what they are doing and you can communicate intent. However, if the check-in agent believes that it is "not allowed" or if they don't know how to push the right buttons to get the AC BP and connecting bag tag to output, then resign yourself to just getting a boarding pass for the domestic flight, picking the luggage up in PEK, schlepping it upstairs to departure level, and rechecking it. Usually PEK baggage handling is efficient and the entire process of picking up at baggage claim and then disposing of it to others' custody will not take up too much of your time. Should you be heavily laden, carts are free and they'll be plenty of them around to grab.

Note that with 12 hours until departure to YVR, you may not be able to go to the AC desk and check the stuff in that early. In which case, the solution would be to put the stuff in Left Luggage (for a fee, of course), then fish it out a couple of hours before departure and check in. I have heard that the Left Luggage counter on the Arrivals level outside Baggage Claim is a little cheaper than the one on the Departures Level before check-in (go figure). Once you have temporarily parked your bags, you can then enjoy the rest of your time on the non-secure side. Maybe leave the airport and go roam in town for a bit, or head for a spa. If you are able to check-through in KHN, or if you pick up in PEK and can immediately check-in with AC, then you of course are free to go airside to wait out your time, but even the *A lounge there gets a bit old after a couple of hours.