Peranza grew up in Cheliax and is also, as it happens, a masochist both by nature and now also by Subirachs's retraining.
This isn't a level of pain that would break her. Losing sight in one eye is unnerving but that's the obvious thing for a torturer to do, right, it's not even evidence about whether you're about to lose the other one, which they won't do because then they can't show you things to scare you.
But she's invented an ilani theory of being tortured over the last few minutes. It says that your reaction to any torture should be the same as your reaction to the most severe possible torture, so that you're not giving the adversary any probabilistic evidence about how much something hurts or whether they need to torture you any harder or whether anything you're saying is true.
So Peranza is screaming like her soul is being ripped out of her, and sobbing something about how Asmodia has secret superpowers, Asmodia made her do it.