Jesus H. They’ve been at this for how many years now and they haven’t coded the game to be able to simply delete 3 items from a stack of 5 to complete a quest? That’s a pretty basic function found in nearly every game, especially MMOs. You either code it that way or code it so that you can no longer pick up quest items once you’re reached the required number, or they no longer appear as loot…etc…
If they can’t even be bothered to fix something so simple I think I may have to delete this one off my watch list.