Hello Christoph,
there no custom maintenance view to configure the translation of tax codes. If you need to do it, just login under another language - the fields with the translation would be available for maintenance. We usually use LSMW project for the purposes of uploading translations. It's easy to configure and the file with data will contain just three columns - e.g. LAND1, MWSKZ + TEXT1 - where the LAND1 stands for country, MWSKZ - for tax code and TEXT1 for description in local language.
Hope this will help you!
Best regards,
The Wirtschaftsmann!