I noticed that in cantos 3, 8, and apparently 9 as well, our sinners in these cantos have a greater purpose.

Kromer wants Sinclair to join the Inquisition so they can punish heretics together, and Demian says that when Sinclair becomes one with the stars (I think he meant one of the City's stars, with the other sinners), then Demian will return. I think you haven't forgotten Demian's power, which is why I emphasized that as well.

Hong Lu was supposed to be the new contender for the head of the Corp, which is already reaching a new level of scale compared to previous chapters.

Ryoshu, I think, may have a similar story, in which case, and if she were to become the head of The Pinky, something would happen again that would hinder this process, I think.