shaker style cabinets are a modern euro design and should have a modern square design for crown moulding and I'd to wanted the angle 52\38 or the 45 degree crown it should have been in the plan from the start. if your ceilings are uneven, it's easier to make them look good with straight square crown, if you have angled crown, it would be harder and more noticeable that your house is crooked.
I usually drop the cabinets down to allow for crown but on uneven ceilings I drop them down an extra inch so not to deal with ceiling unevenness but use a cove crown and nothing too of a Victorian style
Q
Great ideas for top of cabinets
Q