On the subject of "new elements semi-accidentally creating potential inconsistencies" in SW, I think that the Separatists in the prequels would have had a cultural impact that would have carried over more into the OT era, specifically their name.
Palpatine gained his power by (secretly creating and controlling and) really pushing the threat of the Separatists. Anyone who balked at the kind of control Palpatine was taking would have been accused of having "anti-republican / separatist politics" and would have suffered for it, and I don't think that kind of propaganda goes away overnight. And to hold his Empire together afterwards, it's important to continue demonizing anyone advocating for independence from the Empire.
Under the Empire, in SW stories, all anti-Imperials tend to be called "rebels" because that's what they are, but also because we're used to calling them that thanks to the OT. In-universe, within the Empire, thanks to the prequels and associated media, a lot of Imperial Core citizens should probably also regard the Rebel Alliance as "separatists" because the term is already culturally synonymous with dangerous radicals, traitors, rebels, terrorists, warmongers, and so on. The original group of Separatists are either dead or have been absorbed back into the Empire, yes, but I think that the political term as a weapon should probably still be around.
Child Leia Organa was probably called a separatist by one of her peers for expressing any support for independence. There are probably insufferable in-universe debates about whether or not having "separatist politics" means you endorse the monstrous actions of the CIS, and whether or not the political identity can be reformed.
Meanwhile, all that said, isolated people like Owen and Beru Lars, who have little personal experience with the Republic and none with anything the CIS did, might still privately think of themselves as "separatists / anti-republicans" of a sort because to them that maybe just means the Empire ought to leave their planet alone. As Outer Rim people, they might have been getting more Separatist propaganda than Republican, if they got much of anything. In their view, the Republic became a damn Empire, so maybe those Separatist folks were kind of right, actually?
Anyway, I'm imagining the aftermath of "A New Hope" in which Leia is trying to talk to Luke about wider galactic politics, and this Outer Rim farmboy who just blew up the Death Star says something like, "Well, I originally wanted to join the Imperial Academy just to follow my friends and get off Tatooine, but politically, I guess that me and my family have always been pretty separatist."