The tarball of the new 5.9.0 release does not contain any translation (i.e. .po files under a "po" top-level subdirectory), and also the po-related CMake machinery in top-level CMakeLists.txt. I think this might be due to the new release being created manually from the git repository, rather than using the KDE release scripts that do this. This is a regression compared to previous versions.
Thanks for the info, I already noticed this and I'm working on it. Same for the KGeoTag release I did the same day. This happened caused by an issue with releaseme, cf. https://mail.kde.org/pipermail/kde-devel/2022-September/001291.html
Maybe it would be the best to withdraw the tarball and re-release 5.9.1 including the translations to avoid confusion … I already filed a Sysadmin ticket about this.
The underlying tarme.rb problem has been fixed meanwhile, and I did x.x.1 releases including the translations. Sorry for the mess …