... should prove that, as a simulation, this universe of Wizard 2.0 does not suffer the (potentially) same time travel rules as the real world does.

Everything the characters do when interacting with past or future versions of themselves is geared toward maintaining what they know of the timeline. This is especially true of the Brits, and most pronounced in book 5... but...

Virtually everything Brit (any) does in this book creates a Missing Parent Paradox. With the initial confrontation between Brit and Philip, it's an older Brit that enlists a younger Brit to take notes while the older Brit engages Philip. After the confrontation, the younger Brit says she needs to look over her notes, then go back to enlist the younger version of herself... We're missing the parent event that caused the confrontation in the first place. Younger Brit would never have known what Philip was doing without the older Brit clueing her in.

The core event of this book is a Missing Parent Paradox! Brit the Elder would never have had a memory discrepancy without the interference of Brit the younger. Brit the younger only created the discrepancy because because she was told there was one. Again... we're missing the root cause of the whole event chain.

All that said... if the characters are afraid of destroying their universe by causing a paradox in which events in history differ they should be equally terrified that they are, in fact, living in a Paradox of their own making. In fact, they live on layers upon layers of these paradoxes already.

Right from book 1 we're basically told to ignore time travel paradoxes! The characters have already drastically changed medieval london from historical norms and explicitly mentioned in that book how doing so had absolutely no effect on their "present" time periods.

I really do enjoy this series, but I pray one of these characters figure out their worry over paradoxes is pointless. They've caused way too many already. They're in a computer program. Time does not function the same in a computer program.

Lol... had to rant a little. Sorry.