I tested the Japanese app, in in a bit of a hurry, but here are things I noticed.

- 1 time when matching pairs, two different sounds played. Not the automated and presumably yours, but two different sounding sounds. E and another one I think it was.

- One run the male voice played when I clicked on the Japanese symbols to the left when matching pairs. All the other times it played together with the automated voice.

- The error log empties itself despite not leaving the current run, so you can't see what you did wrong. Not sure if it's page specific, but if so it ties into this next point.

- When matching one symbol to four different sounds, the page transition is too abrupt. This is also a thing on the other pages. I'd say better UX here is to give feedback that you did it right, and let the user choose to continue. A score too, if you'd like to "gamify" it.

- The options for modifying runs doesn't work. I was interested in seeing the other tasks, but even when only enabling the task or tasks I wanted, I kept only getting match the pairs and match the symbol to the sound.

Really enjoying reading you blog posts. Currently taking notes into my own Obsidian instance based on your post “Obsidian vault setup tour”

Thanks for sharing