The above is a partial list, Edna supports about 30 langs.

To add another one, you need to find library that implements CodeMirror mode for that language, add it to package.json and update languages.js

It's based on Monaco Editor, which is the open source base of VSCode - you can see the full list of supported languages by clicking the dropdown on the bottom right (similar to VS code: https://code.visualstudio.com/docs/languages/overview#_chang...)