The plugins are multi-language ready, but they don't have much translations yet (Only English & Dutch). However you can quite easily translate the plugins by yourself. The plugin decides based on the language setting of your WordPress site, which translation it will load.
An easy way to translate the plugin is by using special WordPress Plugin: Loco Translate. You can easily add new languages via this plugin.
By the way, I will gladly refund a part of the purchase costs via paypal if you send the translation files afterwards so I can include it in the package for other customers. There are quite some lines you can translate, but you can skip more than half of it if you want to translate the front-end only.