Try taking line 523
$post_item .= '<span class="standard-post-date" itemprop="datePublished">'.$post_date.'</span>';
and putting it below line 494 and 492
so it says
if ($post_format == "link") {
$post_item .= '<h2 itemprop="name headline">'.sf_link_post($postID).'</h2>';
$post_item .= '<span class="standard-post-date" itemprop="datePublished">'.$post_date.'</span>';
} else {
$post_item .= '<h2 itemprop="name headline"><a href="'.$post_permalink.'">'. $post_title .'</a></h2>';
$post_item .= '<span class="standard-post-date" itemprop="datePublished">'.$post_date.'</span>';
}
Make the same change for all the other post types!