> (defcustom org-clock-clocktable-language-setup
> Contributions for other languages are also welcome.

Here's Norwegian Nynorsk:

  (setq org-clock-clocktable-language-setup
        '(

          ("nn" "Fil"      "N"  "Tidspunkt" "Overskrift" "Tid" "ALT" "Total tid" "Filtid" "Tid stempla ved")

          ))

Looking forward when I can delete that line from my init.el :)