commit 882f0867632e964d7cf8371eab077ee524020360
Author: Wolfgang Ziegler // fago <fago@wolfgangziegler.net>
Date:   Thu Aug 13 15:29:05 2015 +0200

    Make sure validation is added.

diff --git a/includes/entity.inline_entity_form.inc b/includes/entity.inline_entity_form.inc
index 480a077..6b71db0 100644
--- a/includes/entity.inline_entity_form.inc
+++ b/includes/entity.inline_entity_form.inc
@@ -272,19 +272,17 @@ class EntityInlineEntityFormController {
       field_attach_form($this->entityType, $entity, $entity_form, $form_state, $langcode);
     }
 
-    // Process multilingual and shared form elements.
-    $this->entityFormSharedElements($entity_form);
-
+    $this->entityFormTranslation($entity_form);
     return $entity_form;
   }
 
   /**
-   * Marks shared form elements or hides them if the user has no access to them.
+   * Handles entity translation for inline entities.
    *
    * @param $entity_form
    *   The entity form.
    */
-  protected function entityFormSharedElements(&$entity_form) {
+  protected function entityFormTranslation(&$entity_form) {
     if (($handler = module_invoke('entity_translation', 'get_handler', $this->entityType, $entity_form['#entity'])) && !$handler->isNewEntity()) {
       $form_langcode = $handler->getFormLanguage();
       $langcode = !empty($entity_form['#parent_language']) ? $entity_form['#parent_language'] : $handler->getLanguage();
@@ -346,6 +344,7 @@ class EntityInlineEntityFormController {
           }
         }
       }
+      $entity_form['#element_validate'][] = 'entity_translation_entity_form_validate';
     }
   }