I was thinking more along the lines of either a behind the scenes reference, like how the Halo series has always had an obsession with the number seven and makes tons of references throughout the games, or potentially a reversal of a certain Latin phrase, Omne trium perfectum, “everything that comes in threes is perfect.” Sel has been known to use foreign languages in the past. Notice that it talks about perfection, something that runs counter to this game. Reverse that and you have imperfection, which can be seen as bad things happening.
This was my point with the weird seasons, we could guess based on when certain things like holidays happen, but remember that the seasons are all out of whack, they are so messed up that this may actually prove unreliable and backfire on the guess we make, pointing us in a completely wrong direction.
On the teaching style, now this is potentially identifying. Their familiarity suggests they've been around him a while, this isn't their first day or the early part of the school year when they are still getting used to him.
