whenever killing a boss needed for quests with quantum sword it does not count for quest completion
unsure if this is a mod or pack issue, so i put this here :)

I believe that is just the nature of the quantum sword—using it is essentially the same as using a “/kill” command, so there is no loot or credit to the player.

For game play this makes sense too—why get credit for killing a boss when it was effortless?

i mean i can stand there in quantum armor (invincible) and hit the boss for a minute or one hit it with the quantum sword.
also you get the loot for the boss and get achievements too, just not the quests