Adding a new language - AdKats/BFACP GitHub Wiki

To add a new language fork the project and create a new folder in resources/lang directory with the language code. Copy the contents of the en folder and paste them into the new folder. Once you've done that go ahead and modify them. In some cases you may see an entry that has a placeholder. These are prefixed with a semicolon :. Do not translate these or modify them, you can however move them around for that entry if it needs to be. The placeholder ends when their is a space after it so just be aware.

You can read the offical docs on how this works if you're still not sure.