While I won't confirm or deny anything, I really like this analysis and I can't wait for what you got to say about Chapter 1 and 2! Things like this make it worth it to work on Nerus for me. But I'll point out one detail you might've noticed but not thought too much about: besides adding or modifying lines, sometimes lines are outright omitted from the backlog. This is also deliberate.
If my memories serve me right this also happens in the later chapters, but the only time I witnessed this during the Prologue was when Neru was talking about the 'Redd Manor' file. Seeing how you pointed this out, I can assume that this is relevant to either the story or the characters, or even both. (Or maybe more worldbuilding which helps us determine how the story will progress later on.)
Now that I'm thinking about it, what can the backlog really record? Does it record everything? If so, why don't some of these get recorded? Is there a limitation to the backlog? Is there a difference between the backlogs and the records?
This also puts the authenticity of Pyre accounts about the backlog/Carcass into question. Was he lying? Was he telling a half-truth? Or was he being entirely honest, that the Carcass does record everything, but the permanency of those records is not as we thought they were? This can explain how one of the memories was nearly deleted but is also contradicted by Pyre saying "If there are no records about you, then you are a newborn!" since if you have no records, assuming that deleting records also applies, you didn't live life yet.
But then again, this can also mean that by deleting memories you also delete the events that happen in those memories, which backs up Pyre's dialogue at the end of the Prologue.
Ahh, too many questions and not enough satisfactory answers.
Well, I'll let my future self figure this out.