It turns out that we have several problems with loading translations in Krita. Qt and ki18n translations seem to follow different rules with regards to users setting a language other than the platform language, on different platforms.
But it also seems that the qm-based translations from the tier1 frameworks we ship aren't loaded at all, unless the user is using distro packages for everything, in a plasma environment. I can see code in ki18n that tries to load the translations for Qt, but the frameworks don't seem to have that startup hook, and I don't know how it's supposed to work... -- https://www.krita.org