Comment # 47 on bug 1027925 from Wolfgang Bauer

Just a side-note:
(In reply to Wolfgang Bauer from comment #30)
> So the translation should actually come from Qt, I think?
> Installing libqt5-qttranslations didn't help though.

(In reply to Wolfgang Bauer from comment #31)
> I think I found it, the translation seems to come from
> plasma5-integration-plugin-lang.

The translation for the "Ignore" button only comes from
plasma5-integration-plugin-lang if you run kdesu in a KDE (Plasma) session,
i.e. if the Plasma integration plugin is used.

On other desktops, that translation is indeed taken from libqt5-qttranslations,
if that's not installed the button is untranslated (and also the OK and Cancel
buttons).

But that should get installed by default now too anyway. ;-)