Hello, I just discovered that 4 Debian packages incorrectly use "cz" for the language code for Czech: http://www.debian.org/intl/l10n/po-debconf/cz
(of course, the correct code is "cs") I reported a bug against each of those, but wanted to let you be aware of that. I think you need to check what package maintainers are doing as, unfortunately, some people are wrong about the correct code for your language. --