Q:

Find out if enqueued script uses wp_localize_script? 

Is there a function that can check if an enqueued script has a call to wp_localize_script attached to it?  

A:

Try this:
function is_localized($tag) {

    global $wp_scripts;

    $data = $wp_scripts->get_data( $tag, 'data' );

    return !  empty( $data );
}

