diff -u b/core/modules/ckeditor/css/plugins/language/ckeditor.language.css b/core/modules/ckeditor/css/plugins/language/ckeditor.language.css
--- b/core/modules/ckeditor/css/plugins/language/ckeditor.language.css
+++ b/core/modules/ckeditor/css/plugins/language/ckeditor.language.css
@@ -9,4 +9,12 @@
+[lang]:after {
+  content: " ("attr(lang)")";
+  font-size: 10px;
+  color: #666;
+}
 
 html[lang] {
   outline: none;
 }
+html[lang]:after {
+  content: none;
+}