The RNG only affects vent orientation, are you sure there's a vent layout that's definitely impossible?
Edit: Oh yeah, and the button is random too, but at least you can see where it is once you're close enough.
No, I definitely have had seeds where the ending hallway couldn't be entered, and even a few where some rooms were fully walled off.
also a few annoying vents where I got stuck
there is no rng to determine which hallways are open in newly entered rooms
Got it