first of all thank you for the theme which is quite comfortable for customization. Unless I do not really know how to translate the theme into German as the English language is not spoken by all our users.
Can you help me with some instructions on how to do the translation and especially where to find the original strings?
To translate your site you may use any multi-language plugin. We recommend you the “GTtranslate” plugin (https://wordpress.org/plugins/gtranslate/) follow the installation instructions to use this plugin.