Solution:If you go to wp-content/plugins/woocommerce-bookings/templates/single-product/add-to-cart/booking.php Line 39, you will see the string which is currently not wrapped in a getText call resulting in it to not be picked up by String Translation.
I have now wrapped the string within the WC Bookings plugin with a GetText call() which allows you to translated it through String Translation. You can find it under the domain "wc-bookings"
