The first question that occurred to me was how the translator handled puns. Because puns exploit word pairs that sound alike but have different meanings, they usually are language-specific. Therefore, they cannot be translated directly. Take the following passage from Chapter Seven:
"And don't take too long, Weasley, the delay on that firelegs report held our investigation up for a month."This exchange depends on the double meaning of arms. Unfortunately, Hebrew has no word that means both weapons and limbs. What the translation does is make Mr. Weasley's report about ekdichay yad (אקדחי יד), or handguns, and the confused wizard calls them ekdichay regel (אקדחי רגל): "footguns." This gets the same point across as in the original--the wizard's ignorance of technology--and creates an equally outlandish image. But it doesn't involve the same level of wordplay.
"If you had read my report you would know that the term is 'firearms,'" said Mr. Weasley coolly.
In other instances, the translation does manage to retain the wordplay of the original book. For example, in the English version Hermione starts a club called Society for the Promotion of Elf Welfare, or S.P.E.W. The Hebrew translation gets lucky on this one, rendering the club's name almost word for word, with the resulting acronym sounding very close to the the Hebrew word for "allergy"!
At least the Hebrew version preserves most of the character names from the original. Many other Harry Potter translations don't. When I posted the "footguns" example on a language list, someone wrote back to me that the Norwegian version changes Dumbledore's name to Humlesnurr. The reason given is that the name Dumbledore comes from a British dialect word for "bumblebee," and humle is Norwegian for "bumblebee," while snurr means "to whirr."
I have no idea how often translators find sensible solutions to these kinds of problems. Puns and wordplay are only the beginning of the challenges. Good translations stand on their own as works in their own right. But they may overstep their boundaries by improving on the original work. One Israeli teenager told Haaretz that he considers the Hebrew version of Order of the Phoenix superior to the English version. That is not necessarily a compliment.