strtolower($_POST[$id . '-url'])

I think there is no need to convert URL into its lower case in rss_pi.php on line 116.
It broke Yahoo Pipes URL

// Loop through feed-rows
                        foreach ($ids as $id) {
                                if ($id) {
                                        array_push($feeds, array(
                                            'id' => $id,
                                            //'url' => strtolower($_POST[$id . '-url']),
                                            'url' => $_POST[$id . '-url'],

https://wordpress.org/plugins/rss-post-importer/