If you use the remark/micromark or markdown-it ecosystem, you have a good news:
I released plugins for remark / markdown-it: GitHub - tats-u/markdown-cjk-friendly: Make CommonMark more friendly for Japanese/Chinese/Korean (CommonMark next specification draft)—plugins & patched packages
Specifications draft is: markdown-cjk-friendly/specification.md at main · tats-u/markdown-cjk-friendly · GitHub
If you bump into any issues, could you post one to here, the issue of that repository, or CommonMark issue Emphasis with CJK punctuation · Issue #650 · commonmark/commonmark-spec · GitHub?