Possibly, but that doesn't stop the theories. You also have a potential point that poses its own questions, what if these 'happy' scenes aren't some divine being's work? What if Maya's supposed involvement in this reset wasn't real? It could be a hallucinogen dropped on or near Kumon-Mi by the enemy and it could be causing Sensei to hallucinate all the crazy stuff going on. Some of it, the normal stuff, is most definitely real, but what if this other stuff that isn't normal and has no rational explanation isn't? That then brings up a further question, why aren't the girls hallucinating if a hallucinogen is involved. Maybe they aren't who they say, maybe they are imposters, enemy infiltrators taking the identities of these girls via this hallucinogenic effect. I'm getting really deep here, I might start up my writing flow if I keep this up and then there will be a fanfiction involved. Assuming these theories ever get me going there, I promise I won't steal your thunder Selebus.
That is another possibility, a sort of Matrix situation and Sensei is one of those who got stuck in it.
Most of it is his thoughts, maybe the 'other sensei' that we see in some of the early scenes that act as some sort of loose memory is the other narrator.
That's what I would go for, but then we lose the potential explanation for her craziness. Appendectomy is a more or less commonplace procedure that wouldn't really fit as some sort of black market extraction, which could serve as an explanation for her craziness depending on the circumstances around that extraction. It could be a surgical mishap, true, but that still doesn't explain her mental state. I'm just trying to fit both her scar and her mental state into one theory here, but I am letting the theories run wild. I don't know of anyone who is just naturally crazy like that let alone anyone naturally crazy like that with a scar of potentially dubious origin. Plus there is a distinct mention of traffickers, which is where the black market idea came from.