Nah. I don't even remember where I read that.
"Another group from Irish legend, the Formorians, were presented as generally deformed. I wonder if that also could be an exaggeration of the Koho's peculiarities?"
The Formorians are described as big, black, ugly and from 'under' the sea. I just figured they were black seafarerers. Albeit, they are reputed to have 'married' some of the later (traceable) immigrants to Ireland. Maybe, 'Black-Irish'?