To complete the world quest “Protect the Root!”, you have to enter the Promise Hill dungeon in Tikatika Colony.
However, while fighting Cicerra, the following boss tip shows:
Defeating Corpse Tailors does not actually stagger Cicerra though. Only the sound effect of stagger happens.
This is a very minor bug, one that no one would probably care about. But for the sake of finding bugs, I’d like to point it out.