As to OP's question, that that loosening is really wierd, Could be not enough tension or using lube on the spoke threads, not on the nipple wheel interface.
Another possibility is that the tire pressure is too high, causing flexing and loosening of spokes. I got this information from a well regarded shop that is building a wheelset for me (I am building a different one myself.....got to get good at it) and they noted that going from a 28mm tires (gp5000) (run and 95 back, 90 front and i am 240) to 32 mm i should drop about 8 pounds pressure and going to a wider rim I should drip another 8 lbs, otherwise there is flexing and spokes loosen. I was multi tasking and so did not get the mechanics down pat, but this could be a consideration
as to all the other stuff
here is a link where the poster said his shop doesn't work on 10 speeds any more
https://www.bikeforums.net/bicycle-m...placement.html
my local bike charity does build wheels and has the full gear high spoke cutting and threading machine, all the park tools and gauges etc.
Bicycle co-ops or bike kitchens are around all over the country
I see a wide mix of skills in local shops, the ones that have been around work on pretty much everything but the knowledge of vintage bikes is going fast. Chain and "trek and specialized" stores seem to focus on sales and some service
Lots of variations even within the county I live in (santa Clara County in CA)