I expected to find whatever code was generating the Nickname and Date & Time info in the "Comment form style" box under the "Comments" tab, but found nothing but formatting info (padding, border, etc.).
So, I pasted:
into "Comment form style" to see if that had any effect on what appeared in a Comment, and it does not.
The %author-description% info does show up in posts with that pasted into the appropriate boxes in "Post/Page info items". (Though it would be nicer if the bio was visible before hitting one of the reply options.)
I am still using 3.3.3, as I was allowing some more time for the dust to settle. Perhaps the new version will make the Comment box editing options easier to find?