Create custom PAGE with register_post_type

Your screenshot seems to indicate that you’re interested in the status message for your custom post type saying 'Page updated. View page'. If that’s true, the reason that you’re getting 'Post updated. View post' is that you haven’t provided status messages for your custom post type.

Here’s the code for the admin edit page (edit-form-advanced.php):

if ( isset($_GET['message']) ) {
    $_GET['message'] = absint( $_GET['message'] );
    if ( isset($messages[$post_type][$_GET['message']]) )
        $message = $messages[$post_type][$_GET['message']];
    elseif ( !isset($messages[$post_type]) && isset($messages['post'][$_GET['message']]) )
        $message = $messages['post'][$_GET['message']];
}

So the edit screen is trying to retrieve messages for your $post_type (agenda), not finding them, and displaying the post messages.

You can fix this by creating $messages['agenda'] with something like the approach described on the Register Post Type function reference:

function agenda_update_messages( $messages ) {
  global $post, $post_ID;
  $messages['agenda'] = array(
    // ...
    1 => sprintf( __('Page updated. <a href="https://wordpress.stackexchange.com/questions/94958/%s">View page</a>', 'your_text_domain'),
                  esc_url( get_permalink($post_ID) ) ),
    // ...
  ); 
  return $messages;
}
add_filter( 'post_updated_messages', 'agenda_update_messages' );