Thank you for the write-up! CJK support is one of those things I’ve been somewhat concerned about.
Do you use a larger font size for e.g. Traditional Chinese in order to make smaller text legible? I’m unsure if it could cause any unexpected layout issues when switching font. Maybe it just works, I don’t know.
When JCash posted about Extension-fontgen a couple of weeks ago, I thought it would be great for CJK when you want to display strings unknown at compile time, like player names etc. I haven’t done any tests with it yet, though.