SEO stands for "search engine optimization". In simple terms, it is a set of practices designed to improve your site’s organic traffic. 

There are a few options you should set to make sure all your comments are indexed. There is no dedicated SEO feature for comments. The meta tags are managed by post content not by comments.

1. In case Google doesn’t index ajax loaded comments of your website you can enable the default pagination. Navigate to Dashboard > Settings > Discussions admin page and check the checkbox in "Break comments into pages with [X] top-level comments per page the [last/first] page displayed by default".  option.

2. For the same purpose make sure the replies are not hidden on page load. Navigate to Dashboard > wpDiscuz > Settings > Comment Thread Displaying admin page and disable the "Display only parent comments and view replies ∨ button" option.

That’s all. Comments are indexed and tracked as post content by Search Engines. So all dedicated SEO features should come from your posts, not from comments. Comments are already ready for indexing and they are being indexed very well.

Related topic: https://wpdiscuz.com/community/general-forum/wpdiscuz-and-seo/