Visual Composer: Where do I find the source code of a custom element?

The problem of not finding the elements was that the installed WordPress version of my template (Cohhe Autorepair) installed a template specific plugin, which was only compressed in the local (offline) template version. Uncompressing the plugin yielded success with

grep "some text" -nr /templateFolder

The final directory was given by:

/wp-content/plugins/autorepair-plugin/lib/functions/shortcodes.php