I know this, since blacks from foreign countries with vastly different cultures than American that also excel in mathematics, don't need this "culturally relevant" nonsense when they were taught algebra and trig.
Example: In the former British colonial countries (including India I believe), what we would consider the equivalent of high school, the students have to take A and O level tests (like the PSAT/SAT/Regents) in most subjects, including math, physics, etc. Those very same tests are given to whites back in the UK.
You don't hear any complaint by Africans, Carribbean blacks, etc. who have to take these tests. They either pass them, do mediocre, or fail.
If they fail, it's because they didn't try hard enough or were just not smart enough. End of story. Even the person who failed will tell you that.
Not over in America -- it's excused away as being "not culturally relevant".