Found a few PHP notices with debugging turned on that should be cleaned up:
Line 1587 - the value of the text box writes out
$_POST["user_email2"] when really it should check to see if that post variable is set. I recommend:
(isset($_POST["user_email2"]) ? $_POST["user_email2"] : '')
This needs to happen on lines 1597, 1605, 1613, 1621, 1629, 1637, 1649, and notably 1662.
From what I can see, this plugin is exceptionally well-put-together and has solved a lot of issues for me all at once. Thank you,