I haven’t read this full thread because I’m late and it’s a bit TL;DR, so sorry if I repeat something.
At first I was upset Cora didn’t get swallowed up by the fire, but I think there is a larger message, one that Christian people and spiritual people may recognize.
Anyone who seeks forgiveness can be forgiven. Everything they’ve done in the past gets washed away. That is what happened to Cora, as terrible, terrible, terrible as she was. She FINALLY sought genuine redemption and forgiveness.
Maybe that is also the point of the Underworld. It’s a place for you to not only finish unfinished business, but this process leads some people, who are deserving, to a path of redemption and salvation.