It’s fine. Nobody will ever notice and anything you do will look worse.

I'd bring the cabinets to the sink with a dark color matched caulk. That will eliminate the shadow.

I'm curious as to how the gap can be wider at the bottom than the top if the sink and cabinet are both square. Is the caulked gap at the rear of the sink wider than the rest?

You could use a drip rail the same color as the cabinets, and caulk to that, as Joe suggests. Apron sink drip rail images.