I DID SOME TESTING AND I FOUND OUT WHAT CAUSED THE CRASHES FOR ME.
It was the Steel Watch trying to arrest me.
If the Steel Watch is trying to arrest me on sight, the game would crash at 33% when trying to load the lower city. If the Steel Watch is chill, no crash.
Are you sure it's not a dead steel watcher with positive HP? That's been the confirmed cause for a lot of people. Seems like a bit of a coincidence that it happened after fighting a bunch of steel watchers!
My second playthrough crashes upon sleeping (invisible loading screen?) having killed only not-Dribbles and his allies and a few Steel Watch in Wyrm's Rock, so I definitely think there's an issue with the metal pricks as my doomed 33% trip to the iron throne on playthrough 1 also coincided with a slaughter at the foundry. Not very easy to pick up their bodies, either...