The ending dialogue with Sentilla ignores the fact that I have seen her unless I visit her on the final day (just before visiting the god with the crown). If I visit her and then go through the time portal to another day, the museum the dialogue behaves as if I didn't meet her at all. ("You must be Sentilla... What monster?" and so on.)

Can confirm this, all the characters act as-if they don't know you, regardless if you actually spoke to them in the last time-loop.

An explanation would be that they simply forgot the last time-loop, but that doesn't hold up because they do remember an Oracle barging in and saving them.

That's something different from what I mean. I did a run where I did save everyone myself before entering the temple, and most of them recognized me. Well, at least those that I saved, not sure about the others.

But with Sentilla, it's my own line that's wrong. If I visit her, reset the time and then finish the game, my character behaves as if he/she didn't meet Sentilla at all, not knowing that she was imprisoned and so on. If I visit her on the last day, it's different, and she remembers me as well, even saying that I was right to not free her on the spot.