Mark from Loomis posted an answer to my request on the Indiana Ballad List. Apparently Loomis just shunted the letters along where the errors occurred. Common sense triumphs. He said he could only remember one example but we have 2 here already including Child 20.

Richie, if you come across any more I'll put them all together on various lists. Plenty of us are still just working from the Dover edition.