I'll suggest that tne reason that there were few Hypergons made or sold is the most obvious one; it is a special-purpose, extremely wide-angle lens.
Not many photographers needed what it did. I've looked at many photographs from the late 19th and early 20th century, more than I could count, and have seen very few that looked like they would have been made with a Hypergon.
And 90 years of 35mm has taught us all to have a number of different lenses in our kit; I suspect that in those days photographers generally "got by" with one lens, a convertible if they were lucky.
That's just speculation, I could be wrong. I do hope that this lens gets made!