Haiku just include NotoSansCJKjp font now, I hope could publish NotoSansCJKcn together. Because many glyphs are difference.
Hello and welcome!
There are two more fonts packages available at HaikuDepot:
Noto CJK Simple Chinese
Noto CJK Traditional Chinese
The main issue is that these font packages are presidentially yuuuge: over 100 MiB. Including more than one of those in the image is not practical. As @un_spacyar said, all you can do currently is get the right CJK package (and probably uninstall the not needed one…).
I only vaguely remember the specifics, but at the heart of it lies a missing feature in Haiku.
The Noto help page says:
Each font sets one language as the default. Note that each language-specific font does support all four languages and includes the complete set of glyphs. However, you need an application program that can invoke an OpenType locl GSUB feature (e.g. Adobe InDesign) to access language-specific variants other than the default language.
Haiku is currently missing the ability to switch to the right version…
Indeed, we should try to fix our font rendering code to be able to do this. But for now, yes, you can install and use the proper font for your language.