[Pinus]

Heck, Microsoft got it wrong — Swedish versions of Windows used to have a folder called "Vanliga filer" (Ordinary files). This was, of course, the "Common files" folder, but the translator, probably having no context, picked the wrong meaning of "common", and chose a Swedish word which does not have the "shared" meaning.

[el-salvador]

In El Salvador (our TLD is "sv") we sometimes get apps or websites in Swedish because "sv" is used as a language abbreviation for Svenska/Swedish. Spotify was like that for months when it launched here.

[Lex-2008]

Another data point:

When Windows 10 just came out, many of apps in start menu had a label next to them, which in Russian version said "Создать" (~Create). It took me some time to figure out that it's a poor translation of "New" (~Recently added). Proper Russian translation would be "Новое".

[r00fus]

The problem isn't the translation, per-se, it's that translation isn't tested (or tested thoroughly enough).

Amazing Microsoft can sell a whole other version of Windows and mess something like that up.

Everything that impacts the user experience needs to be tested.