diff -u b/sources/tmgmt_config/src/Plugin/tmgmt/Source/ConfigSource.php b/sources/tmgmt_config/src/Plugin/tmgmt/Source/ConfigSource.php
--- b/sources/tmgmt_config/src/Plugin/tmgmt/Source/ConfigSource.php
+++ b/sources/tmgmt_config/src/Plugin/tmgmt/Source/ConfigSource.php
@@ -187,7 +187,7 @@
     $data = array();
     foreach ($config_mapper->getConfigData() as $config_id => $config_data) {
       $schema = $this->typedConfig->get($config_id);
-      $config_id = str_replace('.', '_', $config_id);
+      $config_id = str_replace('.', '__', $config_id);
       $data[$config_id] = $this->extractTranslatables($schema, $config_data);
     }
     // If there is only one, we simplify the data and return it.
@@ -226,7 +226,7 @@
 
       // Replace the arrays keys back.
       foreach ($data as $key => $value) {
-        $new_key = str_replace('_', '.', $key);
+        $new_key = str_replace('__', '.', $key);
         $data[$new_key] = $value;
         unset($data[$key]);
       }
diff -u b/sources/tmgmt_config/src/Tests/ConfigSourceUiTest.php b/sources/tmgmt_config/src/Tests/ConfigSourceUiTest.php
--- b/sources/tmgmt_config/src/Tests/ConfigSourceUiTest.php
+++ b/sources/tmgmt_config/src/Tests/ConfigSourceUiTest.php
@@ -351,7 +351,7 @@
     // Submit.
     $this->drupalPostForm(NULL, array(), t('Submit to translator'));
     $this->clickLink(t('Needs review'));
-    $this->drupalPostForm(NULL, array('user_settings|anonymous[translation]' => 'de_Druplicon'), t('Validate HTML tags'));
+    $this->drupalPostForm(NULL, array('user__settings|anonymous[translation]' => 'de_Druplicon'), t('Validate HTML tags'));
     $this->assertText('de_Druplicon');
     $this->drupalPostForm(NULL, array(), t('Save'));
     $this->clickLink(t('Needs review'));
diff -u b/sources/tmgmt_config/src/Tests/ConfigSourceUnitTest.php b/sources/tmgmt_config/src/Tests/ConfigSourceUnitTest.php
--- b/sources/tmgmt_config/src/Tests/ConfigSourceUnitTest.php
+++ b/sources/tmgmt_config/src/Tests/ConfigSourceUnitTest.php
@@ -206,9 +206,9 @@
     $data = $source_plugin->getData($job_item);
 
     // Test the name property.
-    $this->assertEqual($data['user_settings']['anonymous']['#label'], 'Name');
-    $this->assertEqual($data['user_settings']['anonymous']['#text'], 'Test Anonymous');
-    $this->assertEqual($data['user_settings']['anonymous']['#translate'], TRUE);
+    $this->assertEqual($data['user__settings']['anonymous']['#label'], 'Name');
+    $this->assertEqual($data['user__settings']['anonymous']['#text'], 'Test Anonymous');
+    $this->assertEqual($data['user__settings']['anonymous']['#translate'], TRUE);
 
     // Test item types.
     $this->assertEqual($source_plugin->getItemTypes()['view'], t('View'));
@@ -224,7 +224,7 @@
     $language_manager = \Drupal::languageManager();
     $language_manager->setConfigOverrideLanguage($language_manager->getLanguage('de'));
 
-    $this->assertEqual(\Drupal::config('user.settings')->get('anonymous'), $data['user_settings']['anonymous']['#translation']['#text']);
+    $this->assertEqual(\Drupal::config('user.settings')->get('anonymous'), $data['user__settings']['anonymous']['#translation']['#text']);
   }
 }