emotions button not showing

Follow up.
I found a solution. Adding this function to functions.php does the trick.

add_filter( 'comment_form_defaults', 'custom_comment_form_defaults' );
function custom_comment_form_defaults( $args ) {
    $mce_plugins = 'wordpress, emotions';
    ob_start();
    wp_editor( '', 'comment', array(
        'media_buttons' => false,
        'teeny' => false,
        'textarea_rows' => '5',
        'tinymce' => array( 'plugins' => $mce_plugins )
    ) );
    $args['comment_field'] = ob_get_clean();
    return $args;
}