Ain't design grand? Here's my take, FWIW. I would begin with a frank statement of your aesthetic objectives: Is this piece destined to replicate a particular style of furniture, or is it a custom design meant to complement a particular setting? So far, to me, it appears that the form of this piece reflects your interest in early American furniture. Corner cabinets with elements like yours usually had arched base moldings, and it is a design detail that would normally be expected by the eye of the beholder. The question is what are the ideal proportions and detailing of the arch itself? A simple curve like you propose is a bit bland to my eye, based on the various decorative options of period furniture. Visually and mechanically, I might want to have your arch take off perpendicular to the floor and add a graceful dip in the middle. Practice with various inflection points for this curve to see where it should change directions, to your eye at least.
I would disagree that an arched base molding should dictate arched doors. Personally, I would not arch anything else in this design. Google images of "antique corner cabinet" and note that historically, arched doors are not common, and the ones that are tend to be the more highly stylized versions with Palladian style arches that don't reflect the base styling. Traditional cupboards had simpler, straight top rails, and that's what resonates best, again IMO.
Your take on Krenov's grain orientation is fine, although for this cabinet, I wouldn't be in favor of running the rails all the way across. To me, that would confuse the aesthetic of this furniture form. It would look more in keeping with a modern take-off.
As far as "lifting" the piece, typically this is done with a cornice molding. An uncomplicated cove would be my choice. I'd like to see a drawing showing all the elements in place before adding any further critique.
My 2¢, hope it doesn't confuse the issue any more for you.