Translation:You had been tired
the "correct" english translation is simple past, not past perfect. Shouldn't it be "you had gotten tired" or "you had been tired?" (reported)
This is right. A lot of verbs such as -choka indicate entering into a state - eg. in this case "getting tired" rather than "being tired". To indicate the resulting state (being ...) you use the perfect -me-
Umechoka means you're tired now - the getting tired is in the past with present effects, as indicated by -me-.
To say that you were tired at some point in the past, you use ulikuwa to get back to that point in the past and then umechoka to indicate that the becoming tired was prior to that, with effects continuing up to the time in question. "You had gotten tired" and "You had been tired" are probably also possible interpretations, but this is the way to say "you were tired".