That's a nice attempt at theorizing, but I don't think there's a correlation between the race of a subject and the quality of the HT sculpt it's based on. I mean, have you seen HT's Thriller Michael Jackson or Sam Jackson (Octopus) from The Spirit? Holy hell, those are two of what I consider HT's best sculpts to date.
It is only because they do so many more caucasian sculpts than Asian that one could easily conclude that all their Asian sculpts are spot on. But there are probably the same number (or more) of caucasian sculpts that are just as good. It's just that the white peoplez get more attention (byproduct of popular culture and movies) that there are more opportunities to miss the mark, whereas - ironically - HT doesn't do a whole of product based on Asian actors.
Also, it's not like one sculptor at HT works on the sculpts, they have a team of people (and sometimes they outsource, i.e. Hellboy's sculptor Gorae) who work on these magnificent little portraits.