Update to Drupal 8.1.8. For more information, see https://www.drupal.org/project/drupal/releases/8.1.8

core/modules/node/migration_templates/d6_node.yml

@@ -6,7 +6,10 @@ deriver: Drupal\node\Plugin\migrate\D6NodeDeriver
 source:
   plugin: d6_node
 process:
-  nid: nid
+  # In D6, nodes always have a tnid, but it's zero for untranslated nodes.
+  # We normalize it to equal the nid in that case.
+  # @see \Drupal\node\Plugin\migrate\source\d6\Node::prepareRow().
+  nid: tnid
   vid: vid
   langcode:
     plugin: default_value

core/modules/node/migration_templates/d6_node_translation.yml

@@ -0,0 +1,52 @@
+id: d6_node_translation
+label: Node translations
+migration_tags:
+  - Drupal 6
+deriver: Drupal\node\Plugin\migrate\D6NodeDeriver
+source:
+  plugin: d6_node
+  translations: true
+process:
+  nid: tnid
+  type: type
+  langcode:
+    plugin: default_value
+    source: language
+    default_value: "und"
+  title: title
+  uid: node_uid
+  status: status
+  created: created
+  changed: changed
+  promote: promote
+  sticky: sticky
+  'body/format':
+    plugin: migration
+    migration: d6_filter_format
+    source: format
+  'body/value': body
+  'body/summary': teaser
+  revision_uid: revision_uid
+  revision_log: log
+  revision_timestamp: timestamp
+
+#  unmapped d6 fields.
+#  translate
+#  moderate
+#  comment
+
+destination:
+  plugin: entity:node
+  translations: true
+migration_dependencies:
+  required:
+    - d6_user
+    - d6_node_type
+    - d6_node_settings
+    - d6_filter_format
+    - language
+  optional:
+    - d6_field_instance_widget_settings
+    - d6_field_formatter_settings
+    - d6_upload_field_instance
+provider: migrate_drupal