When these two characters showed up in the anime I was confused. I thought that perhaps my memory was just really bad

Same.

the changes to the story order and pacing have been big improvements over a straight adaptation.

Not sure I agree. Not saying the anime does it badly, but I liked the slowburn of the manga and now that I’m reading this I’m not sure how I feel about them combining the two arcs into one. It’s bound to skip a whooole lot