多亏了@cybmeta，我才能够解决我的问题。下面我发布了所有相关代码。请记住，它指的是使用4种自定义分类法（“意大利”、“法国”、“西班牙”、“世界”）的“分销商”自定义帖子类型。

// add columns
function add_distributor_columns($table_columns){
  $area_column = array(\'area\' => \'Area\');
  $macroarea_column = array(\'macroarea\' => \'Macroarea\');
  // put them on the right position
  $table_columns = array_slice($table_columns, 0, 2, true) + $area_column + $macroarea_column + array_slice($table_columns, 2, NULL, true);
  return $table_columns;
}

add_filter(\'manage_distributor_posts_columns\', \'add_distributor_columns\', 10);


// add contents to columns
function add_contents_to_distributor_columns($column_name, $id){
  global $post;
  $post_id = $post->ID;

  if($column_name == \'area\'){
    $italy_areas = (array) get_the_terms($post_id,\'italy\');
    $france_areas = (array) get_the_terms($post_id,\'france\');
    $spain_areas = (array) get_the_terms($post_id,\'spain\');
    $world_areas = (array) get_the_terms($post_id,\'world\');

    $areas = $italy_areas + $france_areas + $spain_areas + $world_areas;

    if(!empty($areas) && $areas[0] !== false){
      $areas_names = array();

      foreach($areas as $area){
        $area_name = $area->name;
        $areas_names[] = $area_name;
      }

      echo implode(\', \',$areas_names);
    }
  }//end if

  if($column_name == \'macroarea\'){
    $macroareas = array();

    if(has_taxonomy(\'italy\', $post_id)) $macroareas[] = \'Italia\';
    if(has_taxonomy(\'france\', $post_id)) $macroareas[] = \'Francia\';
    if(has_taxonomy(\'spain\', $post_id)) $macroareas[] = \'Spagna\';
    if(has_taxonomy(\'world\', $post_id)) $macroareas[] = \'Mondo\';

    if(!empty($macroareas)) echo implode(\', \',$macroareas);
  }//end if

}// add_contents_to_distributor_columns

add_action(\'manage_distributor_posts_custom_column\', \'add_contents_to_distributor_columns\', 10, 2);


// add macroarea filter
function add_filter_by_macroarea() {
    global $typenow;
    $post_type = \'distributor\';
    $macroaree = array(\'all\',\'italy\',\'france\',\'spain\',\'world\');
    $selected = isset($_GET[\'macroarea\']) ? $_GET[\'macroarea\'] : \'\';

    if($typenow == $post_type) {
      $html = \'<select id="filter-by-macroarea" name="macroarea">\';

      foreach($macroaree as $macroarea){
        $s = ($macroarea == $selected) ? \' selected="selected"\' : \'\';
        $html .= \'<option value="\' . $macroarea . \'"\' . $s . \'>\' . $macroarea . \'</option>\';
      }

      echo $html .= \'</select>\';
    };
}

add_action(\'restrict_manage_posts\', \'add_filter_by_macroarea\');



// add contents to filtered list
function convert_id_to_term_in_query($query){
  global $pagenow, $post_type;

  if($pagenow == \'edit.php\' && $post_type == \'distributor\'){
    $selected = isset($_GET[\'macroarea\']) ? $_GET[\'macroarea\'] : null;

    if($selected && $selected != \'all\'){
      $terms_ids = wp_list_pluck(get_terms($selected), \'term_id\');

      $query->query_vars[\'tax_query\'] = array(
        array(
          \'taxonomy\' => $selected,
          \'field\' => \'term_id\',
          \'terms\'    => $terms_ids,
        )
      );
    }// if selected
  }// if right page
}// end filter

add_filter(\'parse_query\', \'convert_id_to_term_in_query\');



// UTILITY FUNCTIONS ---------- //

function get_taxonomies_info($post_id = null){
  if(!$post_id){ // if not passed, try to get the ID
    global $wp_query;
    $post_id = $wp_query->get_queried_object_id();//current post id
  }

  global $wpdb;
  return $wpdb->get_results($wpdb->prepare("
      select tax.taxonomy as taxonomy, group_concat(tr.name) as term_names, group_concat(tr.term_id) as term_ids
      from " . $wpdb->prefix . "term_taxonomy tax
      INNER JOIN " . $wpdb->prefix . "term_relationships rel ON tax.term_taxonomy_id =rel.term_taxonomy_id
      INNER JOIN " . $wpdb->prefix . "terms tr ON tr.term_id = tax.term_id
      WHERE rel.object_id = %d
      GROUP BY taxonomy
  ",$post_id),OBJECT_K);
}

function has_taxonomy($taxonomy_slug, $post_id = null){
  if(!$post_id){// if not passed, try to get the ID
    global $wp_query;
    $post_id = $wp_query->get_queried_object_id();//current post id
  }

  return array_key_exists($taxonomy_slug, get_taxonomies_info($post_id));
}