diff --git a/core/lib/Drupal/Core/Datetime/DateFormatter.php b/core/lib/Drupal/Core/Datetime/DateFormatter.php
index fc78d9e..31f06cc 100644
--- a/core/lib/Drupal/Core/Datetime/DateFormatter.php
+++ b/core/lib/Drupal/Core/Datetime/DateFormatter.php
@@ -232,9 +232,6 @@ public function getSampleDateFormats($langcode = NULL, $timestamp = NULL, $timez
    *   formats, NULL otherwise.
    */
   protected function dateFormat($format, $langcode) {
-    if ($format == 'custom') {
-      return NULL;
-    }
     if (!isset($this->dateFormats[$format][$langcode])) {
       $original_language = $this->languageManager->getConfigOverrideLanguage();
       $this->languageManager->setConfigOverrideLanguage(new Language(array('id' => $langcode)));
diff --git a/core/modules/config_translation/src/Form/ConfigTranslationFormBase.php b/core/modules/config_translation/src/Form/ConfigTranslationFormBase.php
index c4dfa10..54c8a85 100644
--- a/core/modules/config_translation/src/Form/ConfigTranslationFormBase.php
+++ b/core/modules/config_translation/src/Form/ConfigTranslationFormBase.php
@@ -176,6 +176,7 @@ public function buildForm(array $form, FormStateInterface $form_state, Request $
       if ($form_element = $this->createFormElement($schema)) {
         $parents = array('config_names', $name);
         $form['config_names'][$name] += $form_element->getTranslationBuild($this->sourceLanguage, $this->language, $source_config, $translation_config, $parents);
+        // Merge, if there any form attributes from element.
         if ($attributes = $form_element->getFormAttributes()) {
           $form = array_merge_recursive($form, $attributes);
         }
diff --git a/core/modules/config_translation/src/FormElement/ElementInterface.php b/core/modules/config_translation/src/FormElement/ElementInterface.php
index e58ce86..c9fb0b9 100644
--- a/core/modules/config_translation/src/FormElement/ElementInterface.php
+++ b/core/modules/config_translation/src/FormElement/ElementInterface.php
@@ -71,7 +71,7 @@ public function getTranslationBuild(LanguageInterface $source_language, Language
   public function setConfig(Config $base_config, LanguageConfigOverride $config_translation, $config_values, $base_key = NULL);
 
   /**
-   * Allows providing form attributes for the configuration form.
+   * Allows to provide form attributes for the configuration form.
    *
    * @return array
    *   An array of form attributes.
diff --git a/core/modules/config_translation/src/Tests/ConfigTranslationUiTest.php b/core/modules/config_translation/src/Tests/ConfigTranslationUiTest.php
index 807307c..f8def2a 100644
--- a/core/modules/config_translation/src/Tests/ConfigTranslationUiTest.php
+++ b/core/modules/config_translation/src/Tests/ConfigTranslationUiTest.php
@@ -446,6 +446,9 @@ public function testDateFormatTranslation() {
       $this->drupalGet($translation_page_url);
       $this->assertText($label);
 
+      // Make sure date library added from the element form.
+      $this->assertRaw('core/modules/system/js/system.date.js');
+
       // Update translatable fields.
       $edit = array(
         'translation[config_names][core.date_format.' . $id . '][label]' => $id . ' - FR',