gistfile1.txt

  $city = 'Rome';
  
  // Get term id of city. taxonomy_get_term_by_name don't work because it
  // don't works with multilingual values.
  $query = new EntityFieldQuery();
  $query->entityCondition('entity_type', 'taxonomy_term')
    ->entityCondition('bundle', 'property_country_city')
    ->fieldCondition('name_field', 'value', $city, '=')
    ->addTag('term_is_child_of')
    ->addMetaData('parent_term_id', $country_id)
    ->addMetaData('account', user_load(1)); // Run the query as user 1.
  $result = $query->execute();
  // If country ex
  if ($result) {
    // Use existing city.
  }
  else {
    // Create new city.
  }
  
  
  
---------------------------------------------------------------------
  
  
/**
 *  Implements hook_query_TAG_alter().
 */
function MY_AMAZING_MODULE_import_query_term_is_child_of_alter(QueryAlterableInterface $query) {
  $parent_term_id = $query->alterMetaData['parent_term_id'];
  $query->addJoin('INNER', 'taxonomy_term_hierarchy', 'taxonomy_term_hierarchy', 'taxonomy_term_hierarchy.tid = taxonomy_term_data.tid');
  $query->condition('taxonomy_term_hierarchy.parent', $parent_term_id);
}