The de-localization of the category namespace does not work when the category contains a colon. E.g. [[Kategorija:Files uploaded by User:Kikos]] is left untouched.
As of now, links with multiple colons are intentionally excluded from the de-localization, because they might as well be multi-step interwiki links. We need to look into the Linker to see how it distinguishes between colons that are part of an interwiki prefix or namespace, and colons that don't have a meaning (as in the example above). It might be that we can't distinguish this, because we are doing this on Commons (which is English), not on the source wiki.
Reported here: https://www.mediawiki.org/wiki/Topic:Vq0aehpbuvdu4cma