Thanks for the contribution, do the language files get overriden even if they are named zh_CN? or did you try to edit the en_US file?

The program's overwrite mechanism replaces all files in the entire language directory. I previously tried directly creating a zh_CN folder, but after restarting the server, all files in that directory disappeared. My workaround was to modify the JAR file by adding the zh_CN files directly into it, and then specifying zh_CN in the configuration file—only then did Simplified Chinese take effect. That's exactly why I submitted this pull request.