A simple solution to world boss kill problems would be to just have every world boss in game to spawn at the same time. This would give many people many chances to kill a world boss during spawn event. A universal message "World bosses have spawned". Then follow up with "Blank has defeated Blank boss in Blank area." That way people know which zones have been cleared and still have the ability to head to another zone that isn't cleared.
I also believe as more of a personal preference would enjoy it if bosses in larger zones, AD, Wander's Woods, Wild Beyond for 3 large examples, for the world bosses to be 'glued' to whatever screen they spawn on. In other words they don't move off screen from the one they appear on. I say this because unless you get blessed with a lot of luck, they usually take a very very long time to find. So much that many refuse to even hunt for them. I know from experience that Ali Khan and Bloody Mary have taken over an hour to find(my kill) and that is non stop clicking in that time frame lol.
Just my friendly opinion on how to improve the World Boss fun.
(edit for typo)