Upiorek
Anna Studniarek is Polish translator for most of Cosmere books, but not for Mistborn, which was translated by Aleksandra Jagiełowicz. I think that she initially planned to translate (some of) names to their Polish equivalents, similar to what Jerzy Łoziński had done with The Lord of the Rings, (sidenote: n.b. negative feedback which Łoziński’s translation received is probably the reason for most Polish translators to think twice before they change any original name.) but she changed plans. She left a single unnoticed “Upiorek”, a translation for the name of one of characters, Spook. (sidenote: “spooky” can be translated as “upiorny”) It’s one of these things you start noticing when you re-read books, but it still took me a minute to connect the dots.