To help everyone play this mod better, I have created a Japanese translation of ja_jp.json and Chronicle of Shadows.
I was able to send it from “Create new file” as ja_jp.json, but Chronicle of Shadows is a folder, not a file, so I couldn't figure out how to send it.
Does anyone know how to send it?

You can submit the change as a pull request to the repository. If you want to package the localization externally, you can bundle it as a resource pack:

apoth_jp.zip
--pack.mcmeta
--assets
----apotheosis
------patchouli_books
--------apoth_chronicle
----------ja_jp (your translated files live in this folder)
------------categories
------------entries