Yeah, sadly I don't see how it's possible either. Restorative justice was owed to the slaves, not their great-great grandchildren. I just don't see a way of making slavery right that isn't broadly arbitrary, hugely divisive, and likely disatisfactory to all concerned.
But we can look at problems today and fix them. There are bright, straight lines to be drawn between Jim Crow and redlining and the problems that many poor African Americans face. Fixing those problems is a moral duty and it's one that can help people who are suffering today.
It's not perfect, maybe it's not enough, but at the very least it's a meaningful place to start.