Is it just me or is the audio not yet working on this language?
There is no audio for Klingon yet.
(And we don't have an ETA for audio, either.)
Is there ever going to be audio for Klingon
Well, never say “never”… but not anytime soon.
duoling says "tlhIngan Hol vIyajbe'." means "I do not understand Klingon., I do not understand the Klingon language."
but when you write that it says it's wrong.
Above those two answers, there should be a note saying something like “Correct answers include:” — at any rate, with plural “answers”.
Please just type one answer at a time, not two or more at once.