Do comments have revisions like posts and pages? If so, how would you access those revisions?
No, WordPress only provides revisions for posts.
The “History” link on the admin/comments page does not show any editing/changing/updating of the comment, whether done by the admin or the original commenter.
This is actually added by Akismet and not something WordPress itself provides. It acts as a moderation history of sorts, but only Akismet related actions e.g.
Note that I’d edited the comment pictured, yet that edit was not recorded.
If no comment history is available, how would I add that capability via a filter?
Adding it via a filter would require existing infrastructure that doesn’t exist, you would need to build it from scratch, and there is no correct canonical way to do it. In my opinion this would lead to lots of competing alternatives, none of which are more correct than the others. You should ask this as a separate question.