One cannot really compare 14th century Siena with 20th century Western Civilization. Catherine of Siena did indeed do krazy hard and terrible penances. We are not called to do the penances she did, we have not been given the graces that she was given to perform them.
Most all Catholics in their right mind that know what Catherine did would be mortified by them, but that does not make Catherine mentally ill.
Trying to understand everything that makes up Divine Providence will make your brain implode.
You seem to be focusing on a lot of difficult things, distressing things!
I like Catherine, but I’m not planning to try and do the same penances she was doing. We can follow the example of saints in another way than just copying their behaviors.