I'm still trying to figure out who owes them money, land, etc. Unlike what happened to Native Americans, slavery was a private issue that was legally allowed. The US government did not sell or buy slaves from the best of my knowledge (probate court is a real stretch).
Do the original sellers (traders) in Africa bear responsibility? How can we find out who the people responsible were and get money from them? Are the original buyers liable? How do we find out who owned who and settle up?
Honestly, I'm not sure anything reasonable can be done to satisfy groups like this. Concessions only feed their appetite just as we've seen with all SJW types.