Previous attempts at that idea made it so Leia is giving her life-Force to be channeled through Rey into Kylo. This would explain how Rey is able to heal a fatal wound without dying like Ben. But you’ve taken another approach, actually, making it abundantly clear that Leia is summoning Han from the netherworld of the Force and the effort of that is what kills her. I think that’s a really cool idea, as well. The only (slight) problem with the idea is Ben’s line of “You’re just a memory” since in this case Ben isn’t hallucinating and his dad really is there with him because of Leia’s sacrifice.