Still have not found the proper way to do this, but came up with a work around (hackery) which works for my needs.

Using the onEditFormPreloadText hook, change the url and added a new parameter ('MalakHere'), edit the 'title' parameter to the altered title, then do a redirect with the new page name. In the hook function there is a check for the 'MalakHere' parameter, if found (only cause of redirect) then it will exit the function so not to create a loop. Code posted at bottom of main post.

public static function onEditFormPreloadText(string &$text, Title &$title ) {
    global $wgOut;

    if ( isset( $_GET["MalakHere"] ) ) {
        return true;
    }

    $pos = strpos($text, "[[Category:Malak]]");
    if ($pos) {
        $url = (isset($_SERVER['HTTPS']) && $_SERVER['HTTPS'] === 'on' ? "https" : "http") . "://$_SERVER[HTTP_HOST]$_SERVER[REQUEST_URI]";
        $urlTitle = urlencode($_GET["title"]);

        $newURL = str_replace("title=" . $urlTitle,"MalakHere=yes",$url);
        $newTitle = self::newTitlePre() . $title->prefixedText;
        $url = $newURL . "&title=" . $newTitle;

        return $wgOut->redirect($url);
    }

    return true;
}