IMO, this is how it should have gone down. Black never dies in the Black arc. Instead, he becomes semi-good and participates in the tournament of power for U10. Him vs Trunks. Trunks confronts Black. At first Black is interested in Goku but he decides to fight Trunks before he fights Goku. As Goku Black Rose fights SSJ Anger Trunks, Black wants to push Trunks further.

Now from what we can tell, Super Saiyan Anger is an enhanced state beyond SSJ2 (maybe beyond 3) triggered by Anger. Goku Black pushes Trunks and presses his button to raise the power of Super Saiyan Anger at a point where Trunks is now able to fight Black. Black ends up winning after a tough battle. But Black is eliminated by either Toppo/Vegeta/or Goku.