I've used a lot of them personally, especially games. Some of those translations were pretty good, and some were so bad they were actually hilarious, and have become a meme (like "wasted → потрачено" in GTA San Andreas)
I know one indie game whose Russian localization was done and distributed with the pirated version first, before being adopted by the dev and added to the official distribution. (of course since the guy is only doing gamedev as a hobby, his stance regarding piracy of his own games is quite relaxed)
Decades ago I patched binary Commodore 64 applications to have messages in Spanish, getting as far as patching programming environments like Logo and BASIC to have not just error messages but also the keywords translated.
Even without source code it is somewhat doable, and modern applications often have localization mechanisms that remain in the compiled executable.