"It is a striking feature of this ballad just how different these forms and refrains are."

Indeed, Richard.

"...the English "Bow Down" variant (Child Y), minus the resuscitation but with punishment, was brought to America in the mid-late 1700s"

That's what I've suspected for some time, Richie. Like many of the most popular Appalachian ballads, it most likely went over from England.