The book Anatomy of a Typeface by Alexander S. Lawson mentioned that Bruce Rogers was hired to adapt his typeface Centaur to the Justowriter.
As the Justowriter offered only the same limited proportional spacing as the IBM Executive typewriter, the results were, of course, mixed, as the book noted.
I wondered what it did look like, but I could find no source for an image of the typeface.
I have now found a page on the "Computerarium" web site
with a Justowriter brochure including a sample of Rogers on its back cover, so my curiosity is now sated. As well as there being a specifically named and identified sample of the typestyle on the back cover, the sixth page of the brochure appears to be in Rogers as well.