What linguistic qualities are the hardest to translate?
Oh, all of it. Translation is impossible! And I don’t just mean it’s really, really difficult, but really, it’s not actually possible. There’s not a single word in any of the languages I translate that can map perfectly onto a word in English. So it’s always interpretative, approximate, creative. Anything that is, itself, a ‘linguistic’ quality will by definition be anchored in a particular language — whether it’s idiom, ambiguity, or assonance. All languages are different. There are congruences between languages that are more closely related, of course, but those relationships are very much in the minority.