Thanks for the information.
I’m using Google Japanese Input but have never got such an issue so far.
Perhaps, it is related to this topic:
You mentioned that the app freezes after disabling Japanese IME.
So, I guess the IME would not be causing the issue. I don’t know at the moment.
Does it happen with Google IME?
Freezing with hjkl sounds weird.
They are just cursor motion operations, so nothing should block the UI.
If you found any ‘patterns’ to reproduce the issue, please let me know.