Float out the ceiling with mud. Paint. Done.

I'm guessing your ceiling is the problem. Do I see some discolored areas on it, maybe from water damage?

Its hard to see in that photo .The ceiling is clean no stains .

Its slanted from left to right .

Yes, I can see it by looking at the space between the top of the left door and molding to the space on the other side. If that top cabinet is level then it is your ceiling that is sloped. Leave it, you won't see it when everything is in.

Use a level (the kind with a bubble) to check and see if the cabinet is installed straight. Then use the level on the ceiling. It does look like the ceiling is slanted.

Maybe just a plain piece of wood with no lines or decoration that matches the cabinets would make the slant less obvious.

That is hilarious! It looks like the trim carpenter actually cut the top first part of the crown to fit the slope! It is shorter the further to the right? I think it is a wall problem. I think you could remove the top portion of the "crown" and have just a plain piece of flat wood (painted of course) run across and fit to space. But that would drive me crazy forever!! Sheetrock and might even be a framing issue. If the framing isn't done right, then the sheetrock just follows suit and on it goes. Make them fix it. Period.

A closer photo would be nice, but it now appears to me that the ceiling needs a tapered filler to the left side to compensate for the ceiling. Its probably not 2 inches (maybe 3/4?), but the moulding on the ceiling needs to be parallel with the cabinet to accept the crown. Otherwise the crown must twist to fill this gap.

If this is the case, youll have to decide to have a filler or actually level the ceiling. The filler would probably look much better than what you have now. Or of course you leave it alone.

The ceiling is crooked . It slopes to the right

so maybe we put in track lights (small) to cover , But have to worry about the size or else we cant open the cabinets. 2. we lower the cabinets a bit straighten the molding to the cabinets and fill in the top?

What's the big deal? Some joint compound and some sanding and you will never be able to tell. At extra cost, if course.

some joint compound and sanding? Thats a lot of space .