That footnote points to an uncredited trekplace article from 2004 that itself has no citations. There was never an “original vision" that Klingons have bumpy heads, that was an idea entirely original to TMP.

Anyway, how do we feel about the Star Trek III redesign? In TMP it was one hairless bump that was supposed to represent a spinal column, running all the way from the back over the cranium. TSFS and onward, suddenly it was a flatter, wider set of ridges that was localized only to the forehead, with a full head of hair behind it. For some reason I’m always seeing people act like those are the same design, but to me the differences are glaringly obvious.