While following the development of the Ladybird browser[0] I found out many of the Web Platform Tests[1] are related to CJK rendering which I found surprising, but seeing this it makes a lot more sense.
I thought those were on CJK encodings like GB 18030 and Shift-JIS? (Absolutely massive and one of the few places you’ll still encounter the insane stateful four-charset monster that is ISO 2022, so deserving of a lot of testing.)