Does the meaning of -zuri change if it's applied to a thing, rather than a person?
E.g. for "nyuzi nzuri" I wrote "beautiful threads", but it was marked wrong, and the correct answer was given as "nice threads".
At least in English ... I think in Swahili you'd use mavazi instead of nyuzi, although I wouldn't be surprised if it did turn out that people also said nyuzi ...
Your answer should have been marked correct. -zuri can mean beautiful or good or similar things.