Попробуйте так
add_filter('wpglobus_hreflang_tag', 'filter__wpglobus_link_items'); function filter__wpglobus_link_items($link_languages) { foreach ($link_languages as $key => $item) { if ($key == 'ru') { $link_languages[$key] = '<link rel="alternate" hreflang="ru-RU" href="http://veinmedical.com/"/>'; break; } } return $link_languages; }
***91;$key***93; заменить на [$key]