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I've seen かむやまといわれびこ, かんやまといわれびこ, かんやまといわれひこ, かむやまといわれひこ, and, perhaps most revealingly, かむやまといはれびこ. I suspect all of these merit mention somewhere in the article, but which should we give as the "main" one inline? Some IPs have been edit-warring over this, presumably based on the fact that Nussbaum (an unreliable source written by someone who probably didn't read modern Japanese and translated by someone who almost certainly didn't read modern Japanese, let alone classical Japanese) uses one spelling in the cited article.
As far as I can tell "かんやまといわれびこ", and "かむやまといはれびこ" is just an archaic spelling that most educated Japanese readers would know to read as though it said "かんやまといわれびこ", is the most common pronunciation in modern Japanese (and so is the pronunciation most likely used by Japanese scholars of the Kojiki when talking about the topic), and, as User:Nishidani's footnote makes clear, it's kind of anachronistic to use modern Hepburn orthography in an attempt to reflect pre-modern Japanese pronunciation anyway.