This part of the review struck me:
"It was really lucky that Harry now had Hermione as a friend," from the "Quidditch" chapter, becomes "kai hermaion dê ên tôi Hareiôi to Hermionên nun echein philên" (p. 147) -- lovely and idiomatic use of "hermaion", lovely pun on Hermione's name, lovely "dê".
Indeed. (Hermaion: "a god-send, wind-fall" according to Liddell & Scott.) But note that the Greek translation now has a wordplay that is not present in the original English. In Biblical studies, occasionally we hear that a certain work or part of a work must have been written in Language X, because a wordplay is present that is only possible in Language X. However, as this example shows, a clever and adept translator might introduce wordplays where none existed in the original. My guess is that such translators are the exception rather than the rule; but we might do well to keep the possibility in mind. The better the translator, the more skillfully he will hide his tracks.