Yeah if it weren't for Han and Luke the Force Dyad would have ended as an Ahch-To hermit and a DS II hermit, lol.
Speaking of Han how do you interpret his appearance?
It sounds like the JJ cut had him as nothing more than a fabricated Force Projection by Leia. I don't like that (and is another reason I'm fine with JJ's version staying buried forever.) If it's just Leia doing another puppet show then that's two straight films that Ben was manipulated by Force Projection.
I know that it goes against SW tradition of only Jedi appearing as ghosts but for me the Han scene only works if it *is really him.* Disney wisely insisted that it be open to interpretation because I take it as Leia using the Force to assist in bringing Han's spirit out of the netherworld so that the two of them could legitimately interact. That isn't totally without precedent either since it was decided by George and Kasdan that in ROTJ it was Ben and Yoda that were able to help Anakin become a ghost after he died (hence his body not disappearing.)
So I think that's what Leia did for Han. If it isn't him then it doesn't actually make up for his murder at all since the real Han would have still died tragically with no reconciliation whatsoever.
It wouldn?t make sense for Han Solo to appear as a Force ghost because he didn't use the Force and didn't have the proper training to return as a Force ghost after death. Additionally, the interaction the two have is nearly identical to the one presented in The Force Awakens. This gives the impression that Ben is remembering the moments before he killed his father, a memory that has haunted him ever since. Leia was not there for this conversation so its very unlikely she would have known what was said between them, so it couldn't possibly be a projection from her. I guess we can call it "a force memory projection" by Ben. Han even looks the same and has similar posture to the last time Ben saw him. It was Ben's way of coming to terms with his inner darkness and what he did to his father (he made the wrong choice), by asking Han for forgiveness and reciting the exact dialog on the bridge (I know what I need to do but I don't know if I have the strength to do it)- and making the correct choice this time- he is finally able to find inner peace within himself and thus end his torment (which really began at the end of TFA after he gutted Han)
Lastly, The fact that he's a memory projection by Ben is very important to Ben's arc. If it was Leia's force projection that helped Ben turn, it would have been a moment of divine intervention to bring him back to the light. The fact that the memory came from inside Ben means the entire dialogue with Han was internal and Kylo's redemption actually came from his own heart.