To follow up on the Grime Gremlin paragraph, I just wanted to reinforce that I was not trying to say that I personally view sanitation jobs as mundane and unfulfilling, but just that the MC does. I actually think if you had the other custodians responding to the threat as it develops rather than being like some kind of SCP group it would have made it a lot easier to sell the parallels of protecting the school from a major threat and the day-to-day activities of just keeping the place clean and tidy. Like if the attitude of the staff was "Just another way we have to keep the school clean" I think that could go a long way to shaping the MC's opinion of them and moving him in the direction that they represent much more than a "dead end job".
Also, yeah, caught the Night 1 thing because while I have quite a bit of experience writing, reading, and reviewing spooky monster stuff, I have no experience in sanitation work. So I can assure you whatever gaps in logic happened in regards to the latter went way over my head.
Appreciate the in-depth response! Love to see dev teams interacting so much with the comments.