I’m no expert, and this is my first submit in this forum, but I thought this might help. I personally went for a different direction than the one described in the author.php template.
if ( $coauthors_plus->is_guest_authors_enabled() ) {
$coauthor = $coauthors_plus->guest_authors->get_guest_author_by( 'user_nicename', $author_name);
}
if ( !empty($coauthor) ) {
echo 'Guest';
}else{
$coauthor = $coauthors_plus->get_coauthor_by( 'user_nicename', $author_name );
echo 'Member';
}
From ther you can use the $coauthor variable to get all the meta information you need. Like
<?php echo $coauthor->display_name; ?>
<?php echo coauthors_get_avatar( $coauthor, 90 ); ?>
<?php echo $coauthor->description; ?>
Hope it helps