I found your search for stone mason guilds and training very interesting. This week a friend posted photos on his fb page of the stone cutters and
craft guildsmen of Italian origin who lived in Barre, Vermont and created quite a community. They were not Jewish. However, a thought comes to mind that perhaps there were immigrant corners of immigrant Jewish people who were employed in the task in the making and engraving of graves stones and markers. Would it be valuable to follow a path of these artisans in this country, Canada, England and France another countries to see if some of these families were multi generational and some came to North America to work in this profession here?
Incidentally, my friend was so moved to photograph some of the graves and memorials because the people buried underneath died during the last Pandemic, the Influenza Epidemic of 2018 and onwards, noting the beauty of the work and the tragedy of their deaths during a Pandemic
I hope these thoughts are helpful,