Regatta, in particular, ought to have been easy, since it's basically a Spanish word—the main Spanish language sailing magazine in Puerto Rico is called La Regata, and there are regatas up and down the coasts of Mexico.
But the large point is that although I know what a regatta is, I have never seen one, and I don't personally know anyone who has participated in one. I learned about regattas by reading about them in a book. And that's what the Scholastic Aptitude Test is about—your aptitude for learning things from books. And if your culture isn't much into reading books—Sotomayor's wasn't—then you don't have a "cultural bias" problem, you have lower scholastic aptitude.