It took me some time, but I'm partial to the idea that AmIOkay is another Maya or part of her. AmIOkay might even be what happens if someone isn't brought back in time as has been somewhat alluded to. As far as there being multiple AmIOkays, I don't see anything stopping that from being the case, my only guess would be that AmIOkay needing to be a version of Maya that has gained enough insight into the resets and world before being reset to turn into her. I think it's also possible that her personality is simply split or erratic, and/or she's influenced by her location and possibly one of the user(s).
As far as Maya having been reset in the first place, and possibly leaving the note before-this, it might seem strange at first. But as far as I'm aware, we're not told outright that Maya has been doing this continuously, from start from cycle one. Even if she had a role to play in starting the cycles through her connection to the shrine or wish, she never says or is said to have (from what I remember, please correct) that she was there during the first reset or caused it, and hasn't stopped. She's just been doing it for a long time, but a long time out of an uncountable or an infinity is still just a small percentage. Even if she thinks she saw the first cycle, it's possible that she's wrong, if her memory of previous cycles was gone.
As far as the note, it might not seem like it makes a lot of sense either, but I think there's a couple ways to justify it being there. One is that the board seems to be an afterthought, for Akira specifically, just a board with old sticky notes on it that he only really looks at with much care during resets. Another is if Maya really has been reset, it's likely she's gotten to a point of trying to do something about it before. Like I said I think having enough knowledge or otherwise would probably be a prerequisite to having an AmIOkay appear after you're reset. Maya Prime had seemingly tried everything she thought of to fix things, which would give her reason to leave the note, but also call into question why she never did but a previous Maya did. Maybe Maya Prime is a dumbass. This is all a little speculative, though.
As far as these several hidden places go, they may not be the same exact thing, but I feel like they all have to have some correlation. Aramaug summed it up better than I can. It just irks me. I'm a sad boi. Had a train of thought before being dragged to the bar against my will last night. Must think more about what these places mean metaphorically.
