Ceiling – Yellowing around crown molding

There is visual evidence in photo A3 of one or more interior renovations constructed with less than workman-like quality.

Given the age of the house and what portions of the original construction remain, I it would be common for a house of this age to have had a load bearing wall perpendicular to the ceiling joists when originally constructed.

If there was previously an interior load bearing wall perpendicular to the ceiling joists, it's purpose would have been to reduce ceiling joist deflection. The cracking in the ceiling finish is symptomatic of deflection beyond the strength of the finish joints.

I recommend consulting a structural engineer familiar with residential projects of this scope. The condition is probably repairable given a reasonable budget, but it is necessary to first know what exactly needs to be repair.

If the gap bothers you that much, you have a few options.

Fill the gap

You could fill the gap with wood putty, or color matched caulk. You'll still have a gap, but it will be difficult to see.

Remove material from the molding

You could remove a bit of the material from the back of the molding, to allow it to lay flat over the lip of the cabinet. This will likely make the mitered joint between the two pieces of molding look odd, as the bottom of the pieces will not mate.

Remove material from the cabinet

You could remove a bit of the material from the cabinet, to allow the molding to lay flush with the side of the cabinet. Depending on how far out the cabinet overhangs, this might also look a bit strange.

Learn to live with it

The easiest approach, is to simply learn to ignore it. Not many folks will notice it, and after some time you probably won't either.