In medieval times a crowder or crowther was a player of a crowd - usually taken to be a prototypcal crwth. Post reformation, outside of Wales, the word appears in English and especially Westcountry dialect for a player of any sort of fiddle. As the crwth was quite widely known in 18th century Wales the word may have had a more specific meaning there, I defer to my Welsh colleagues on that point!

I'm not aware of crwth tradition crossing the pond, though it's quite possible that Welsh emigrants may have taken the crwth with them. I would be surprised if the word crowder, meaning fiddler, had not gone to the United States and Australia with Cornish miners in the 19th century.

cheers

Crowdercref,