In the search tab, the package summary and the description (hidden under the "deatiled information") is translated only for "Istalled Packages," but not for "Available Packages". As an example, try searching for "pam-devel" with LANG=cs_CZ.UTF-8. Analogous problem is present in yum, see bug #251891. (Observed with pirut 1.3.9.)
*** This bug has been marked as a duplicate of 251662 ***