The template after_verify.tpl in the second line uses "$user->username", but
"$user" is not known.
To have the user-name, take "feu_smarty::get_username($feu_uid)", "$feu_uid" is
known.
Here my second line, corrected:

<h3>{$mod->Lang('msg_welcome')}
<span>{feu_smarty::get_username($feu_uid)}</span> <em>({$feu_uid})</em></h3>
instead (commented)
//   <h3>{$mod->Lang('msg_welcome')} <span>{$user->username}</span>
<em>({$feu_uid})</em></h3>