In releases 3.0.4, 3.0.5 and 3.0.6 there were two files - czech.inc which was corrupted, and czech2.inc that looks ok to me. I have no idea what has happened but the good file seems to have been removed and the corrupted file has been kept in the release.
I replaced the inc-file with the old one (czech2.inc from the 3.0.6 release), now everything looks fine from the technical side.
As I do not speak Czech, I can not judge about the content, but my Czech colleagues will complain if something is wrong.
Awesome! It’s important to link the forum thread to the mantis (you usually do think I think) because then when we make the release blog I thank the people in the forums too