"Terrible weather" cannot be correct, as it is possible to say "il tempo terribile". "Awful" is OK, but "bad" is really the best response. But I agree with you that not enough people have given feedback for these later lessons!
Despite a word existing for terrible in Italian, I have found that Duo is usually quite happy to use one Italian word to translate various English ones. "Brutto" was used to translate terrible in another sentence for" terrible words"