Hello,
I’ve translated the CommonMark specification into Japanese (excluding the help and the tutorial).
You can view it here, and the repository is available here.
The setup uses po4a with a newly added CommonMark module that I implemented. The setup for translation is complicated at the moment (the GitHub workflow is quite dirty, for instance), but I hope it may be useful as a reference for others working on similar translations.
Thank you, and feedback is welcome!