If you haven't contacted the author yet I can tell you that the Imfelds originally came from Lungern (http://www.lungern.ch) in the canton of Obwalden. I've been there and still there are a LOT of Imfelds.
I remember doing some research when I was in school. But I don't know if I still have it and if those you're doing research on are connected to me. The history of 'my' Imfelds dates back a long time. 1100 AD as far as I can remember.