Ditch It. It doesn’t work.

Won’t tile ending right where the bay window ceiling starts look weird?

I dislike those above sinks they make th windows hard to open and IMO if you must it shold be tiled on the shelf for sure . IMO tiling to the ceiling might be the wrong choice and that tile can be done later after all the cabinets ar ein place then see what is needed

The bay window sill/shelf is above the countertops, not flush.

Even worse how will you ever open the windows I am tall and would have hard time as for the trim IMO you match the trim to the rest of the house then figure out how the tile goes regardlwess that ledge needs a waterproof counter if plants were the plan for that window