70 languages from one guy? Was this vibe-coded?
Beyond that, some of the Japanese text didn't exactly match what was being said, and some of it was basically the same thing twice, but once with more emphasis. (An exclamation mark.) As a long-time Japanese learner I knew which to expect would be expected as the answer, but a novice would not and it would be just frustrating.
Another was a whole question spoken out loud, but just 1 word from the question as an answer. It can be used like that, but it's asking a lot for a learner to get through it. It's like asking, "Okay?" when you mean "Are you okay?" and expecting a learner to figure it out.
I'm not really sure who this is for. It doesn't seem to fit well for beginner, intermediate, or advanced learners. Beginners need more basic info and explanation. Intermediates probably need things that are more topical. Advanced users probably need things that are more... Well, advanced.
The UI also hanged the browser for full 5 seconds in places.
Though I do think there is vast potential for such things, it needs to be approached judiciously.
Duolingo (at least for the same language) has correct pronunciation and grammar/words, even if it's not a good way to learn.
If I were fine with AI, I could just prompt the LLM myself to create a course perfectly catered to me. Why would I need you? Because your prompting skills are magic? Yeah, no. That is like charging for google search results because you searching skills are so great.
The whole problem with Duolingo is that it got so much worse once they started using AI. Switching to another AI driven project would be out of the frying pan into the fire.