Leia does distract him. She’s not the one who redeems him, it’s Rey. Kylo starts second guessing his dark path after Rey “kills” him and then revives him. The “hallucination” of Han is a personification of Ben’s internal struggle. He’s reliving a memory of his darkest moment and realizing it could’ve gone differently.
I’ve cut Leia and given Han full retribution. It’s such an awesome payoff and flows much better without Leia at this point.