The reviews in Site Reviews do not support comments. An addon will be introduced at some point to support this. However, they would not be your typical comments so wp-discuz would not apply or suit the integration
Understood, all content is placed via blocks in main section on default. Does Site Reviews have its own database or uses wp_posts to store review data?
Does Site Reviews have its own database or uses wp_posts to store review data?
Both. Reviews are stored in the wp_posts table (Reviews are a custom post type), the rating information is stored in a custom table, and pivot tables are used for review assignments.