I have bantam Buckeyes and they have all manner of chick down from white to brown and striped, but I've never seen one with a spotted face like that. Also, they feather out with light-colored flights, not partridge ones. They only turn dark with the last juvenile molts. I think you might be right. Your guess is as good as mine. I would've expected a little more black but I guess not. I suppose another way to test it would be crossbreeding.