[Theme: Adventure Journal] Redefine functions in child theme

Apart from the stylesheet bug I discovered earlier today, I noticed that you cannot redefine functions of Adventure Journal.
In functions.php it says:

To override ctx_adventurejournal_setup() in a child theme, add your own ctx_adventurejournal_setup to your child theme’s functions.php file.

I tried to redefine ctx_aj_setup(), but PHP will throw an error. I think there is a call to function_exists() missing.

Background: I would like to add the time of a comment, but you would need to redefine ctx_aj_get_comments() for this reason.
(Side note #1: That’s quite an effort just to add a timestamp. Maybe this could be changed to a stylesheet “option” in a future version by using display:none for the timestamp?)
(Side note #2: ctx_aj_get_comments() calls comment_date() using a hard coded formatting parameter. This prevents users from changing the date format via WordPress settings. In addition the formatting string contains unescaped (invalid) XHTML which results in an error: comment_date(‘F j {br}Y’) returns something like “December 23 <bFri, 23 Dec 2011 21:39:00 +0000>2011”)

http://wordpress.org/extend/themes/adventure-journal/

Edit: HTML line break in formatting string does not show in the text above; replaced by {br}