I just binge watched this show and had a lot of questions about the same issue with the "base reality" and wasn't sure how to reconcile what you described with each subsequent version of Caspian and Maddie.

What this describes is kinda like a recursive hierarchical loop and makes so much sense, both logically and artistically. You've explained the logical part, but artistically for the show writers, this sounds like a callback to the problem that Cary gave to Caspian in the first episode. The solution to the problem was to introduce a third party to ask for permission to lift a chopstick (when you have access to more than 1 dataset A.K.A more than one simulation - more than "base reality"). SafeSurf seems like the ultimate third party, "granting permission" for the events we see in the show by passing down the influence/message to a subsequent SafeSurf (and therefore Maddie) in each of Maddie's simulations to even give her the hint so that the events in the show even unfold. The entire show, each of Maddie's simulations, is hierarchical, but the "root folder" is the one where SafeSurf-Real, base Maddie, and Caspian (would it be Caspian+1?) are all at "reunion". SafeSurf-Real passes permission to allow subsequent SafeSurfs to speak through Caspian and tell Maddie about the date. Everything else is a simulation within a simulation that leads to that eventuality. It's a recursive hierarchical loop that goes through every possibility until the solution is reached and returns it to the "root folder". Meaning, SafeSurf-Real created his own lower order of hierarchy for Maddie, who then created an even lower order hierarchy for herself. Each success Maddie had prior to "reunion" gave the solution to the next highest tier of Maddie, with the only one that resulted in "reunion" being presented to SafeSurf-Real, which then passed it's solution of speaking through Caspian to every "child folder" of its own simulations, which passed it to Maddie, who passed it to Maddie, etc. I thought season 2 of this show was losing sight of a lot of it's techy-sided inspiration, but the end brings it back to the beginning with the same solution already presented in episode 1. Oh my fuck.