I have yet to make much of this passage in A Peculiar Treasure:
One of my delights was to have [Grandpa Neumann] take me on his knee and tell me stories of Edelvard and Kunigunda. (p. 25)
I suspect that the personages were Neumann’s own invention.
Tracking down Cutler-Hammer, to which Edna Ferber refers as an important employer in the upper Midwest, is much easier. Although the electrical and electronic products supplier was acquired by Eaton Corp. in 1978, the brand maintains an identity, albeit diminished, to this day.