The COM Register does register/unregister TLB files, and works in our tests...
I don't know german so I can't exactly translate the error you received into English, but it looks like some type of disk error retrieving the type library?
The only required field is for a valid path/filename to a tlb file to be entered in the "filename" field, you should NOT check the .Net assembly checkbox.
If it continues to fail, one option would be to email the tlb file to
support@kinook.com for our testing.