Indeed, if that's the new policy you need to plan as if it won't happen. For me it worked out on an itinerary with two different PNRs. But, connecting time was extensive (six hours I think) and I was on UA in Global First, so they were inclined to be supportive. We would have had time to re-collect luggage and re-check if that had been necessary. In this case, I think you would have to assume it won't be supported. The interline agreement is there, but that's moot given the policy to not check bags across PNRs which you mention. I assume this is because technically 3K in not OW, as I have done it onto a OW airline recently.

IMO if you feel you have luggage that can be carried on board on AA/JAL, I would do just that and turn up at the 3K gate. Worst that will happen is that they will gate check. Your timing is tight for picking up and rechecking the bag.