This is a gap in the current system. Comments are used for things other than pure comments. There is a type field, but not the sort of registration you get with posts, taxonomies, etc.
Comments don’t have a staatus, they have Approved, which is overloaded as status now.
The steps to address were outlined a while ago. Comment type for comment, which is an empty string, needs to be moved to type “comment”, which requires some migration.
Registration functions need to be built, and any place with hardcoded comment functionality needs to be switched to use the registration system.
To keep it simple—as my perception of CP stands—why change the comments to be capable of any deeper meta. If you want custom then you create a CPT which HAS the comment which can be called/renamed anything you want. Therby eliminating the need to add more Registry registration to the post-meta or even comment tables.
Less is better and stopping at as-is is OK with me especially for comments, titles, featured images, tags, cats, excerpts, dates, editor or any other post data. Also this would be better fit as Plugin Territory.