If you are editing a command and adding a new message you should include a good translation in all supported languages (English, Spanish and Catalan). If you can't do it, please say it in the pull request and we will translate it.
When you add a command, you should include an alias for all languages. You also must edit the doc/alias.json and doc/commands.json to add the documentation. If you have any doubts, ask in the pull request.