I translated this as 'mae hi'n filltir o drwch' but it was marked as wrong, but surely 'it' can be 'hi' or 'e'?
You are perfectly correct, that's an option we'd left out. Apologies. That's done now. Thanks for the comment.
Duo still isn't accepting this answer
Exactly what was your answer that was rejected - including capitals and punctuation? If you let us know, we can check it against the currently accepted answers.