Since around Chapter 20 this is actually my guess for the entire basis of magic that Eliezer is working from. That is... there's a jumble of ideas and tropes that are invented and sequentially stolen by one author after another. Someone tells stories of Vlad Tepis, Bram Stoker comes along... and N iterations later you've got Twilight with vampires having extra chromosomes and clairvoyance.

To understand a magical universe at the deepest level is to see the hands of previous authors influencing your physics and history (and possibly your future if you are in a prequel) plus a "current author" who has a measure of finer grained control over things like plotting and characterization - limited by the audience's willingness to play along.

If this theory of magic is right, rationality in a magical universe should lead you to to become genre-aware, and then the next obvious(?) thing is to go meta genre-aware and start trying to "genre hack" your universe and see if you can "tunnel" into the derivative works (or maybe just get the author to fall in love with you or something).

My current working theory is that Dumbledore as figured out a rough outline of these "magical physics" and has been actively manipulating his reality for decades, with the goal of setting up pre-conditions that could create "authorial change" and/or to make a certain story easy to tell given the facts. The more pointed goal is to cause his universe would branch at a "point of interest" in a direction that, according to fictional tropes, is more likely to be to his own liking.

Based on his revelation about pranking Harry's mother, I've got a (totally unnecessarily detailed) hypothesis about what he may have done to create initial conditions for Harry Potter something like 20 or 30 years before the present story (including setting up an abusive adoptive environment) that got Rowling to pick up the canon universe and give him a victory there.

In the meantime, if the theory is true, the deeper question is whether Voldemort has the same insight, and if he (in keeping with the "bad guys are better leaders" trope) he actually told some of his henchmen about his plan for the world. I think Snape might be genre aware? And the Malfoy's are even better candidates because they could be trying to hack the universe such that Draco is the main character in a fairly standard "magical prince from fallen but ancient family, rising to up to a historically and morally appropriate place in the world". Setting Harry up as Draco's evil arch-nemesis would be a good move in this vein... Harry falls into the Lex Luthor trope and eventually loses because "that's how those stories work".

The only trick is that they are actually in a fanfic about rationality!! I'm not sure if anyone realizes that yet. Maybe Dumbledore does now? Eliezer was more obvious about the story with this bit:

"Indeed," said Dumbledore. "But Harry is the hero, so he may be able to do things that are logically impossible."

Which confirmed my hypothesis some. But my plotting hypothesis will not be supported if Dumbledore doesn't start seriously updating on the "science is starting to apply to magic" facts. I'm kind of curious why he didn't notice that Transfiguration was retconned in the first place. In the face of so much else magical chaos that Eliezer left in place that adjustment is sort of glaring. Noticing possible retcons is one of the nearly necessary skills you'd want to cultivate if you were going to genre hack.

I really hope my hypothesis bears out. I'm aware of no previous work of fiction that jootzed all the way to being genre-aware of its genre-awareness and I think it would be it would be hilarious to read one :-)