When I wrote Knoppixpatch, I didn't take into account the differing EN vs DE versions. The patch file is said to work with 060603 version. The patch file I released will only work with the 060603 English version.

a differing EN/DE version is likely to cause mkisofs to complain about a missing boot catalog and fail to create a patched iso.

As I don't have a German copy of the disks, I cannot create a patch set for the German versions. Perhaps someone else can?

Also, the program needs around 3Gb of space. It creates an 850Mb swapfile on-the-fly then removes it before the program terminates. If you don't have enough space on a single partition, you could manually create a swap file on a different partition and disable the part where the script creates a swap file.