It sounds like his writing would be better served if he just tacked on an appendix with all of the magical minutiae.

But by Sanderson's First Law, if it were in an appendix he wouldn't be able to use consequences of the rules in the story. Imagine I Robot if the laws of robotics were an optional appendix (although not quite that extreme).

FWIW, I didn't find it over-explained, but I tend towards systems naturally.

He does tack on an appendix, which adds in even more details. I personally like it, but I suppose I was also the kind of kid growing up who would be okay reading D&D rulebooks. :)

Or just stuff the rules in a fun footnotes when necessary. I've always been a fan of that technique personally, although I understand it is generally discouraged.