I think reason it feels rushed is because we're too used with many stories dragging down the plot and having terrible pacing, I don't think the manga is axed, maybe the mangaka always had this story in mind and is just going through it, I do agree it could maybe be a little slower but maybe the mangaka never planned for it to be a long series
As for Cattleya , I'm not gonna lie, I feel I'm the only one who maybe understands her and think her actions makes sense :V, I think everyone is maybe looking things from the wrong angle, she doesn't have some deep long term objective, her actions actually make perfect sense if you stop to think about the things she said and done so far
Short version? In my opinion she's a misanthrope, she hates how people are, how the world is, in any other story she would be the typical villain that wants to burn the whole world to the ground or at least conquer it, here though she has an alternative, turn every single human and ninyou into youmas, who she seems to see as pure and innocent
The thing is that she's basically insane, youma are really not much different from animals, just infinitely more powerful, but since they're not much differnent from animals they're also basically not evil like humans and ninyou so a world of nothing but youmas would be pure and perfect
You could probably also compare her to those villains who are in position of power and suffer from black and white insanity, she already decided both humans and ninyou are inherently evil due to how the world is, there's no arguing or reasoning with her, she's the kind of character that if she had mind control power she would brainwash everyone into being "good"
Just for the record I understand why many are disappointed with Cattleya motives, the story so far was been pretty vague on what she really wanted and what was her plans, so many of us are basically
disappointed by her motives because it's just basic and plain insanity, you could probably compare her with like I don't know, the Joker, except the Joker is a nihilist that believes nothing matters and that life is a joke so he create chaos while she sees everyone as inherently evil and want to forcefully change that
I always felt that in many chapters you could feel she was just
wearing a mask to hide her insanity, there was always something off with her and we just didn't know what, well now we know for sure, she's fucking crazy :V
At least that's my take so far but I could be wrong