Listing child pages depending on user capability (role)

If the Rol is in the meta you have to get the IDs of all of them then compare the meta access rol to the rol of the user:

    $post_parent_ID = $post->post_parent ? $post->post_parent : $post->ID;

    $title = $post->post_parent ? get_the_title( $post->post_parent ) : get_the_title( $post->ID );
    //we use get posts to get all posts for the given ID
    $children_pages_array = get_posts(array('numberposts' => -1, 'post_status' => 'publish', 'post_type' => 'any', 'post_parent' => $post_parent_ID, 'suppress_filters' => false));
    //we get the user rol
    $user_role = sb_get_user_role();
    //here we create an array that will be populated with IDs
    $ID_pages_rol_array = array();
    foreach ($children_pages_array as $child_page_obj) {
        //we get the rol that can access this page
        $page_role = get_post_meta($child_page_obj->ID, '_members_access_role');
        //do the current user rol have access to this page?
        if ($page_role == $user_role) {
            //yes it does add to the IDs of pages that this rol can access
            array_push($ID_pages_rol_array, $child_page_obj->ID);
        }
    }
    $children = wp_list_pages(array(
        'title_li' => '',
        'include' => $ID_pages_rol_array, //lets send those IDs to be formatted as list items
        'echo' => 0,
        'depth' => 1
            ));

you can get the IDs with get_posts (actually the entire post object) after making the array of permitted IDs, that can be send to wp_list_pages.