Yes and no, Zariel is pursuing Karlach because she absolutely must punish her as an example. Karlach is known in hell as a very skilled warrior; her escape wouldn't go unnoticed. If Zariel were to simply let her escape, it could lead to even more escape attempts, something Zariel, given the dire situation, cannot afford. I'm afraid she would do whatever it takes to punish her as a deterrent as soon as she landed back in hell.
I would say its the other way around, Zariel personally persuing Karlach is a sign of weakness for Zariel to show, Devils only persue traitors and deserters that are on their close social caste. If a Archdevil is pissed running around chasing a slave bodyguard, it reflects poorly on Zariel.
Karlach is part of Zariel's bodyguard entourage, last time i check, this includes more than a thousand individuals. Karlach's escape would be mostly blamed on whoever recruited her, not on Karlach herself (she is property to them, not a person with free will).
Maybe you're right, and in fact, I hope you are. However, it doesn't change the fact that Karlach remains trapped in a place where she repeatedly stated that she'd prefer to die than return. I hope that eventually, one of the gods of senseless death at Larian will speak up to inform us whether there are any plans to fix this absurdity.
