So if i understand correctly, the remember mechanic is more of a way to set the player in the right step in the main story, no like if you didn't get them will put into a bad ending, but they serve as some form of a smooth guide.
As for the unlockable scenes, they are more of a variation of a already written ending, for example, i may had a X ending if Moonie, but by unlocking her scenes i will get XY
If this seems confusing, don't worry, english is not my first language, so sorry for my poor grammar. As for Miel i don't have any issue, in fact, i thought chapter 3 would be the one