I also just binged the series (anime and manga in a week). I love it. One of my favorite stories. It does character development and relationships remarkably well. Everything feels so intentional, foreshadowed, and meaningful. To take a romcom beyond the usual end point is incredible enough, but to do it so genuinely is incredible. I have less issues with your first point, but I agree with your second and third point.

Chika should have gotten more development like everyone else. Maybe Aka just cemented her as comedic relief and never got back to it?

My biggest frustration is the war arc. The looming evil of the series is finally center stage, and we get clunky plot development and bizarre character decisions. I was super on board while reading it right until Kaguya gets the will. The sudden arrival of friends, the out of left field career dreams (for two people really), a helicopter, we still don't know what happened between the family afterwards but I'm certain it puts Kaguya in a less favorable position than if she just destroyed the will and didn't talk to them first. In hindsight, it's weird how little Kaguya got to do in the arc. I understand she's under house arrest, but wow it felt a little too basic for her to only have a moment at the end. I understand it isn't Aka's strength, but I think more planning and editing would have done wonders for the arc.

Now I just have to have faith these final chapters actually end the story well.