There are two parsing bugs in the language files, resulting in not displaying properly. The reason is a wrong placeholder tag in the language files. This occurs in two places:

in lang_tags.php search for {search_tag} and replace it with [SEARCH_TAG]

in lang_upload.php search for {allowed_types} and replace it with (guess what) [ALLOWED_TYPES]

;)

Seem's that I m slowly getting deeper into the script!