PermissionsEx is built to be translatable. Players will be shown messages in their client's locale if the plugin has been translated, and server messages will be shown in the server's default locale.
Currently, messages are only available in English, so we are seeking contributors to translate to other languages.
Overriding messages on your own server
Currently, messages can be changed only by editing the messages.properties files within the jar. There is usually one per package with the messages used in that package.
An eventual goal is to allow overriding messages using files in the plugin data folder, but this has not been implemented yet.
How to contribute
While we eventually plan to put up a CrowdIn page to allow translations to be contributed more easily, the only way to contribute at the moment is to provide new versions of the files in the src/main/messages folder in each module.
Feel free to ask for help in the Discord -- we will be happy to assist in getting more localizations in.