I've just been having my daily go at the Hawaiian course, and noticed that every sentence now appears to have real audio! (I'm not sure if there are gaps, but every random skill I tried had it, and there wasn't any yesterday.)
Thank you to the Hawaiian team—this makes the course a hundred times better at a stroke!
I couldn't see any other thread about this so I thought I should bring it to people's attention.
Edit: came across a sentence without audio today, so there is the occasional gap, but the vast majority seems to have it.
It's morbidly hilarious that this happened just days after I decided to finally get off my butt and finish my Hawaiian tree. That said, it will be useful for me when I review and gain more crowns, but the timing was a bit inconvenient for me, haha.
At least the Hawaiian tree is so short it won't have taken much time to do it audio-less. I'm on the cusp of finishing the Swahili tree, having previously waited months and months before starting it in the hope that audio would be added, before coming to the conclusion that it would never happen and that I had better just do the course without it; now, there is audio—hooray!—but I should have much preferred having it when going through the tree the first time round.
I think this must be an extension of the Duolingo law that says 'if a tree is going to be updated, it'll happen just before you get to the last skill'.