1.php

<?php

function field_language($entity_type, $entity, $field_name = NULL, $langcode = NULL) {
  $display_languages = &drupal_static(__FUNCTION__, array()); // *** This is cache for field languages
  ...
  if (!isset($display_languages[$entity_type][$id][$langcode])) { // *** This is triggered only once, when cache is empty
    ...
    drupal_alter('field_language', $display_language, $context);
      ->
      function entity_translation_field_language_alter(&$display_language, $context) {
        if (variable_get('locale_field_language_fallback', TRUE) && entity_translation_enabled($context['entity_type'])) {
          ...
          $handler = entity_translation_get_handler($entity_type, $entity);
          $translations = $handler->getTranslations(); // *** This is EMPTY as the translations are not loaded
          ...
          if (isset($translations->data[$context['language']]) && !entity_translation_access($entity_type, $translations->data[$context['language']])) {
            // *** NOT TRIGGERED, so no field language filtering/processing happens
      <- // ** returns untouched entity
    $display_languages[$entity_type][$id][$langcode] = $display_language; // *** Wrong language data drop into cache
?>