We believe that the bug you reported is fixed in the latest version of kdepimlibs, which is due to be installed in the Debian FTP archive:
By looking at the upstream revision, it is quite obvious that this does not fix the bug. The erroneous holiday file has just been renamed to holiday_de-by_de. I have no opportunity to test this, but I would expect that the wrong holiday would show up when selecting that holiday region.
Should I better report this upstream? Alex