The matter of racism and xenophobia in the series is definitely interesting worldbuilding from Bakker's part. I do agree that it seems that most Norsirai cultures (at least in the "modern era" of TSA) tend to be seen as the "uncivilized" ones. Having only read the series properly once, it's becoming much more noticeable in the (forum) reread. Conphas' comments in chapter 8 of TDTCB about the Tydonni and Thunyeri that had recently arrived at Momemn come to mind, with him thinking that at least the Ainoni, being fellow Ketyai, were civilized.
Then you have Zeüm, an apparently very advanced society that looks down on absolutely
everyone in the Three Seas as "barbarians". While our opinion on Zeüm might be a bit biased by the fact that most characters we meet in the story were part of the Satakhan's court, and we have no idea how the average Zeümi citizen lives, it's definitely a welcome change to the usual fantasy standards (and hopefully we'll see much more of Zeüm in the near future). Zsoronga and Sorweel's friendship, I think, exemplifies the point you're making quite well - in another series, you might expect the white teenager to be the more sophisticated and knowledgeable one, and here you have Sorweel
completely out of his depth compared to Zsoronga
(well, both of them are actually out of their depth due to the whole situation they're in, but again, I think you get what I mean).
The only exception here is probably the case of the Dûnyain (who
look Norsirai, but honestly should be considered as a separate ethnic group altogether), but they are just above everything and everyone in
so many levels, it's like they don't even "count" as part of humanity anymore in some aspects...
After TUC, we're actually left with the majority of the main cast as people of colour. You have Achamian, Esmenet and Mimara as the main characters that are still alive. Kayûtas and Serwa (not actually confirmed as having survived) do look Norsirai, but I think
technically they'd still count, as their mother is Ketyai? (though the ridiculously dominant Dûnyain genetics don't help much here) Not to mention that the main antagonists are now four Dûnyain/Norsirai.
Anyway, what I'm trying to get to here - I definitely agree with you on the points you've made. It didn't come across as racist, mean or anything of the sort, don't worry.
As a white person, it might not really be my place to address some of these issues in more detail (one is always wary of that), but I really appreciate what Bakker has done in the series so far, and hopefully this trend will carry on to the next series.