Since CoC proposes warning and suspending users for inappropriate comments, consider respective adjustment in software to make this process more transparent. Suggest to show them (deleted) comments that led to punishment, to help them learn what specifically went wrong and what to avoid in the future.
Currently the only way for user to learn is to ask moderator to share deleted comments. This involves moderator load and can't scale.
Related feature request at MSO: Allow users to view flagged comments (over 300 upvotes).
There are probably many ways how this can be implemented but one that naturally springs to mind is to add to user profile a link to the list of "deleted recent comments", similar to how it is done for deleted recent posts.