If your "very-reputable" architect designed a home with a vented crawl space in Nebraska, I'd suggest they're not so reputable in the building science category.

With proper insulation and conditioning of the crawl space, you may find you don't need to modify your heating system. Depending on how the foundation of the crawl space is constructed, you may be able to add insulation to the exterior and eliminate the need to find really, really skinny trade contractors.

A few owners later, the house is now our forever home and we’ve discovered that in winter here in the NE, the kitchen gets bitter cold.

Not sure if she is in Nebraska(NE)? She says 'here in the NE' - or North EAST

Ah, that's where punctuation comes in. New England would be abbreviated as N.E., N. Eng., N. England... North east would be abbreviated as N.E. In either case, a vented crawl space in a cold climate zone is not appropriate, in my opinion.

Right! As long as folks are using the correct punctuation and spelling. We know that this is not the case on Houzz- even with PROS(not you - just thinking of one in particular).

I agree about the vented crawl space.

A sad commentary on the quality of high school English.

Sorry for the confusion, folks. I meant North East :)
But yes, vented crawl space was supposedly code at the time but definitely not a good idea.

Thanks for your help, Charlie Ross! I’m very hopeful for insulation to be enough.
I’m told it’s ideal to install wiring for baseboard before spray foam installed, to avoid drilling holes into the barrier, but maybe it wouldn’t be so terrible to do after if necessary? Exterior is stone, so we will install insulation from inside.

If insulating the exterior isn't an option, I'd pre-wire for whatever you want while you're doing the retrofit and then insulate it.

Not a continuation of the grammar and punctuation sidenote, but some verbage in the OP to me could be interpreted differently: is only the Breakfast Room the addition over a crawl space, but the Kitchen next to it is unbearably cold, or does the Kitchen extend into this crawl space addition? And, could this crawl space be an original part of the house, say a porch with stone piers, and they captured the space? Or, is it a newer CMU addition next to the old stone basement foundation?

Also, your description of "remove HVAC ducts and plywood for insulators" might say something: I'm picturing your ductwork is hanging below the floor joists in a vented crawlspace, and probably uninsulated duct? Only 1 or two ducts for both rooms, and were the runs taken off an existing furnace? Is the bottom of floor joists covered in plywood for some reason?

If it were my house, I would first understand the construction and areas of improvement for insulation and air sealing, then review HVAC. If the entire house is forced air, including the Kitchen and Breakfast, I certainly would not introduce baseboard heating of any sort. Nor electric radiant for such a large area (keep it confined to bathroom tile in a forced air house).

And, if it were a forever home of high market value, I would review whether I could dig the crawlspace a bit deeper (your description is "small and crowded" but if contractors don't like it that would say to me there is no headroom) and simulataneously work on a mud slab/radon/encapsulation all at once.

FWIW: HVAC is any method of Heating Ventilating Air Conditioning, you have forced air. And vented crawlspaces have been and are still to code - that is the cheaper route than an "unvented" and conditioned crawlspace.

Trust me, in the NE, the last thing you want is resistance electric baseboard heating! Insulate, insulate, insulate, first. Get the crawlspace sorted, then insulate the walls (and ceiling/attic if appropriate) and then figure out what, if any, supplemental heating you need.

Resistance electric baseboard heating will empty your wallet REAL fast!

If you have an ample budget, hire a contractor to build or rebuild to solve the issue.