In the "List" tab, the package summaries are translated only for "Installed Packages," but not for "Available Packages". As an example, try looking at "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 ***