Hope this gets to you in time. Not easy to give you a clear answer as I haven't done it in this direction. But given my very recent experience in the reverse direction recounted below, I'd strongly recommend you call JAL at their reservations or HK airport offices to ask about the limit applicable to the entire route - i.e. including the AC sector to Vancouver (YVR).
For a single ticket covering both sectors, and a same-day Narita (NRT) transit, JAL should be able to interline you, checking your baggage through to YVR applying the weight limit applicable to the entire route (i.e. either 32kg or 23kg for the whole route, not separate weights by sector). At NRT you won't need to handle your baggage at all as you said.
If each sector is on a different ticket, and/or your transit halt at NRT is overnight, the same (as above) could still apply, but there are greater chances of their having you collect bags at NRT and handle them yourself with AC as a fresh flight (separate baggage limits applying).
At the risk of making this post long, I'd like to recount for you my recent experience accompanying people to check in at Toronto (YYZ) airport for flights two days apart to illustrate why you'd do well to check first with the airline.
1st Case: Route was YYZ to Chicago (ORD) on United, 4hr transit at ORD, then Asiana to Seoul (ICN), 4hr transit at ICN, same day Asiana flight ICN to HKG. Everything on a single Asiana-issued e-ticket bought on an online travel site. At the United check-in at YYZ they checked in the bags all the way to HKG, but imposed a 23kg limit on each bag (2 bags per passenger). Bags 23-32kg could be taken, but at a $50 charge each.
2nd Case: Route was YYZ to ORD on American (code share with JAL), 2hr transit at ORD, ORD to NRT by JAL, overnight transit 20 hrs at NRT, NRT to Kuala Lumpur (KUL) by JAL. Everything on a single JAL-issued discounted e-ticket bought on Orbitz.com. We'd heard American allows only 23kg on N. American routes and the bags were packed accordingly (2 bags each 23kg max). There were three passengers including two young kids so they engaged a porter at YYZ. The porter called out to the AA checking clerk - Hey Martha, how much weight to Malaysia? She looks up her screen and says 32kg!! A scramble followed with handcarries considerably lightened by transferring books and stuff into the check-in luggage before weigh-in. That was good. It so happened the system would not let AA interline the baggage through at the NRT halt - they'd need to recheck in the bags at NRT next day but the weight allowance would remain as at YYZ check-in.
(As it so happened, at ORD transit, JAL were willing to take the trouble of retagging the bags all the way to KUL without the passengers having to do anything, so the Tokyo halt was a breeze and JAL even gave them free stay at Nikko for their overnight halt).