I am seeing a lot more women from Taiwan in ads and reviews vs K=girls.  Is there a trend?

Ive seen it too. I assumed its C org BS marketing

Unless you speak Chinese and can tell the difference between regional accents and dialects, you're not going to know.  They are doing this to try to position their ladies closer to the price range of Kgirls and Jgirls rather than other Chinese girls, which are generally at a lower price range like Thai-girls.  However, Thai girls are more likely to offer anal than K-,  J-, or C-girls.   If you have a smallish dick and want something tight, go see a Thai girl for anal.