Our plugin uses the standard WooCommerce format to store reviews in the database. It enables good compatibility with many other plugins that also use the standard reviews format.
In the standard WooCommerce format, reviews for variable products are stored on the level of the parent product and not on the level of its variations. This way, the variable product page shows reviews for all variations of this product. Since our plugin uses the same data format to store reviews as WooCommerce, review for variable products will also be stored on the parent product level.
We hope that this article was helpful. If you have any questions about the plugin, please don't hesitate to post them on our support forum or submit a ticket for our support team (available for customers with Pro licenses).