@LiMr notified me categories at Czech Wikivoyage are not ordering articles correctly (as expected by Czech speakers). For example, at https://cs.wikivoyage.org/wiki/Kategorie:St%C3%A1ty, Česko is at the end of the alphabet, while most Czech speakers would expect it to be right after C. Another example is Chorvatsko, which should be ordered under Ch (a Czech letter, located between H and I), rather than under C.
Czech Wikipedia uses uca-cs-u-kn. Let's set the same category collation for Czech Wikivoyage as well.