I wonder what/who is Polymakh? What is Polymakh's Cap (golden crown with cross on it)? Should it be some Pope's cap? I would like to know.
This is a case of intentional butchery of language for effect. In this case mutation of language by time.
Much like Piroman Empire, is in fact the Roman empire. But the brainers are to far removed to get it right.
First to the object itself, it appears to be a version of the crown of the Tsars(from 1498 till 1682) know to us as Monomakh's Cap after it first presumed wearer Vladimir Monomakh. Which seems to getting conflated with polygamous from the context of the of the first sentence.
So two conflated words, intentionally smoshed for prose effect. Thou i personally think polymath is smoshed in as well cause that what Polymakh kinda sounds like spoken aloud.
I would be of the opinion to preserve it as is, since its used as a possessive proper noun.