"I speak Federation Standard."
Translation:DIvI' Hol vIjatlh.
I'm guessing that it was accepted with a typo warning, because jIjatlh and vIjatlh are only one letter off, and a one-letter mistake is usually allowed through.
However, if the one-letter mistake results in another valid word, it should be rejected, and jIjatlh exists as a word... but I'm not sure how to tell Duolingo's marking algorithm that.
You're right that it would have been best to reject it but I don't know how to make that happen.