My ljdump tool downloads all journal entries and comments. If you edit a comment after ljdump has downloaded it, then ljdump will never see the edited comment. After all, it already downloaded the immutable comment body, and does not expect it to change. Even the <date> field in the comment_body download does not change when a comment is edited!
How did people edit comments before this feature? Well, they deleted the old comment and created a new one with changed content. Why not simply automate this process with the new edit comment feature? That way, you won't play havoc with your APIs and people who depend upon them.