I no longer remember the details, but I have vague memories of the idea
behind these tasks/metapackages being to have a mechanism to only install
the relevant KDE translation packages when installing KDE. No idea if it
was ever done for all or any languages, but it seem like a good idea to
avoid having to pull in KDE translations when installing LXDE or XFCE. :)
Perhaps it is already solved some other way? I do not know. Perhaps something
to check out and verify before removing them?