So, it's been several months since I first said I was having fun doing the circuit board layout...and after a few iterations/revisions I finally got an order for two copies of the board submitted today.
The main hold-up on actually getting it submitted was the time to trace/check the board for errors. My husband has a lot more experience with electronics so he was doing the verification - and he needed to be not too exhausted to be able to trace things through (he has FMS, so after a week of work he frequently doesn't have much mental or physical energy left over - progress tended to be limited to long weekends/Easter/etc). Initially there were a couple of layout issues that needed adjustment, and some additional learning for how to put surface-mount chips on the bottom layer of the board in kicad. The end result was a much better board layout, so the adjustments were very much worthwhile. We also found one issue with one chip having the wrong pin layout (footprint) set, so we were able to fix that before it caused us issues in the actual board. :-)
So, now we wait for the manufacturer to check the files and make sure there are no issues preventing manufacture. After that is confirmed it should take a week or so for the boards to arrive (7-day turnaround for their special offer price, which will give me 2 boards at 140x230mm sizing). In case anyone's interested, we ordered them through B.E.C Manufacturing in Queensland Australia - they had a special offer for single design boards fitting into a pair of 7.6 x 10.6" panels (as many as would fit per panel - which for this board was one per panel), which came out to about 1/2 the cost of getting the board pretty much anywhere else. So we'll get a board and a spare, and if there's any issues in manufacture/broken tracks/etc we can pick the best of the two (if there isn't any issues, maybe I'll make a second one someday - at the very least, it'll make a nice "I did that" show piece). Most low-cost prototype circuit board manufacturers have a size limit of 200x200mm for board dimensions. With the keyswitches physically mounted on the board that's too short - we need that space! Without those switches on the board, the connectors to connect/wire the switches in later took up a ton of room and would have required a LOT more effort in assembly, with more stuff that can break due to vibration/flexing/use - and we'd still have trouble mounting the switches and the boards in the box, particularly as we'd have needed two boards at that point since some of the stuff absolutely needs to be near the top/back of the box (wiring length, external connectors), but the space to fit the switch connections only existed at the front/bottom of the box that the keyboard was in - and those two boards would need connections to each other adding yet more jumper wires. Ugh, what a rats nest that would have been! Other small run/prototype board manufacturers charge a fixed price per square inch - which is fantastic for small boards, but after we added the keyswitches to the board those became prohibitively expensive. BEC's special was very much appreciated (and I've been quietly panicking that they'd end it before we got things ordered!).
Having had several more months of playing around with circuit layout now, I'll confirm my initial impressions - it's a fantastic puzzle to solve, which makes it something I found really fun to do!