It could be due to my ignorance but I find odd that WordPress templates rarely offer a customised way to show the comment’s output when the users forget to fill a field (or they fill it wrongly). Usually, they simply call
wp-comments-post.php that shows quite a poor output.
I’ve tried to go over this problem with a patch for Sandbox that is basically a reshuffle of
wp-comments-post.php (with a custom
Here you can download this patch.