That's what I was thinking. The only reason I considered it might still be relevant was that it was being used by Johan Lithvall a guy who designs some really nice hair for AAA's, he did the hair in the Horizon and Spiderman games. I wish Japanese devs shared more about their process for example how Capcom does their hair…
Not particularly, I'm not sure I understand what it is. With Substance painter I regularly release a normal map, basecolor, OcclusionRoughnessMetallic. But I don't have this problem when I import them on max or unreal for example.