Jesus said let the dead bury the dead. There is no restoration once that last breath is taken, that is why the emphasis on seeking restoration here and now.
I wonder if you are misstating what you think here?
No one is suggesting that you seek forgiveness from the dead but that you forgive the dead who have trespassed against you. That you seek understanding by reflecting on their lives and why they behaved as they did. If you find wrong balance it with mercy and generosity, and judge as you would wish to be judged by intent and in view of the crosses that person was bearing. Otherwise your hatred is a stone that lies between you & God.