User blog comment:Kaido King of the Beasts/Chapter 810: Crucify and Chill/@comment-1940096-20151217205027/@comment-208.96.127.154-20151220171905

A good translator knows when to change a colloquialism in the source material into a colloquialism in the language they're translating to. Otherwise, everyone sounds like a robot. Sometimes, a character is intentionaly given a quirk (I don't know if you've noticed any quirky characters in One Piece) that need to be translated into an english equivalent since they cannot be directly translated. What's really important is preserving the intent of the author.

The problems start when you decide to add cultural references for the Western readers, as it compromises the original intent of the material.