Hi,
Sorry for the late, I just noted thee messages in the support forum.
The translation of the drop-down menus are automatic. You can use a WordPress translation compatible plugin to get the translation applied. In the case it doesn’t work please open a private ticket (we offer free support for this plugin) at https://apphourbooking.dwbooster.com/contact-us and indicate there the URL of the page where you publish the calendar and the version number of the plugin (the version number that appears in the plugins menu) to check the case in detail and provide the solution.
Thank you for using the plugin!