The trim i circled is to traditional in style to the ceiling trim if you decide on this simple style I think these 2 should be changed to q simple flat trim no detail

I’m not exactly sure what you are asking but if you are asking about the height difference from one side of the room to the other that’s normal and will show less with the current configuration than if you switched to 40” cabinets.

You should have gone taller for the uppers to make the molding from cabinet to ceiling much smaller . You could have raised the wall cabinets to 21" from the counter to minimize this space . 36" high cabinets would have been much better . Now I think if the cabinets are in there is not much to be done but at least paint the rest of that trim the same as the cabinets.

Could you have the soffit removed and replaced with very short cabinet extensions with glass doors that would allow for display?

We would like the cabinets brought up as close to the ceiling as possible,

40" with some sort of short, maybe1 inch trim. (Or should we keep the style as on thr bottom of the upper cabinets?)
What trim would match the square molding/cabinet doors? Thinking to paint it same as cabinets.
If the cabinet doors are brought up to the ceiling and add a 1 inch trim on top, it will have almost a half inch gap in some places because of the uneven ceiling. So will fill up the gap.

Square molding looks like this in the rest of the kitchen and rooms

If soffits in dome parts cannot be removed. Perhaps FAKE IT with 40inch doors but keep 30 boxes just adjust height.