“Can you be sure psychologically colonized "non-whites" wouldn't use these methods if more modern methods were unavailable?”
But that was after the Meiji era:
https://en.m.wikipedia.org/wiki/Skin_whiteningFollowing the Meiji restoration, men and women reserved white lead makeup and traditional attire for special occasions.[69] In China, Korea, and Japan, washing one's face with rice water was also practiced, as it was believed to naturally whiten skin.[61][70] Historians also noted that as East Asian women immigrated to the United States, immigrant women engaged in skin lightening more frequently than women who did not immigrate.
I may admit your point considering the last sentence, but didn’t the (Faustian/Progressive) “whites” in the US invent those methods in the first place? Also, the US probably invented more methods than China, Korea, and Japan did in one colonial era.
“(I have encountered situations where "non-white" Eurocentrists follow "whites" despite surely knowing nothing about whether or not the "white" being followed is either Faustian or progressive.”
Again, when “whites” expand on it, the Eurocentrists follow along.
P.S. maybe pigmentation is not the best example of a parameter that can be expanded, considering the fact that accurately white skin is the stopping point for it, but the other parameters (as in dimorphism, height, wealth, skill and IQ) can easily be expanded by a “white” while the Eurocentrists will rely on the standards that “whites” already expanded on.
So whether or not it is Faustians expanding on the parameter or colonized Eurocentrists aiming towards the end of it, their confidence will always aim towards the end of the parameter, rather than to aim towards whatever will fulfill their destiny. Won’t it?