“(In other words, if one alien can do it another one could undo/edit their work ad infinitum...)”
Absolutely. And why I believe one entity is protecting us from the other entities and ourselves. But with as little intervention as possible. They are gently steering us towards a progression of historical events that will define their own reality in their present. Yet there are others who would like to derail that future reality.
I understand the argument—but “gently steering” runs into the same craziness (time loops) as all other forms of intervention.
The old science fiction concept was “time cops” who made sure nobody made a mess out of time travel.
Are there time cops?
How effective are they?
What happens when they fail?
There are questions and more questions—and not a lot of answers that make sense.