|invenit novum amicum Greg Heffley—aut inimicum?|
(From the wikia for Diary of a Wimpy Kid.)
The reason is that building reading fluency—in any language—demands that you read a lot: you just have to keep reading more and more in order to cement your vocabulary and a sense of the language. But much of the Latin literature that we have is written in so formal a register that it can be both dry and difficult. (Imagine trying to learn to read English if your only books were Shakespeare, Milton, Hazlitt, and Keats!)** Translating books like The Hobbit or Harry Potter and the Chamber of Secrets isn't just a matter of creating quirky novelty gifts: it's meant to produce texts that are a little more whimsical and a little less challenging than the speeches of Cicero and the poetry of Ovid.
I haven't yet read the Latin Diary of a Wimpy Kid, although I'm excited. Just the Latin title, Commentarii de Inepto Puero, suggests that Gallagher's translation has wit and spirit to it: to any reader of Latin, the title inevitably calls to mind Julius Caesar's Commentarii de Bello Gallico, "commentaries on the Gallic War" (all the more appropriate, since Caesar is writing a kind of "diary" of his own deeds***). Ineptus is an interesting word to use for "wimpy": I'd think first of it as a way to say "dorky kid," "awkward kid," or even "nerdy kid," but the more literal words for "wimpy" as "courage-deficient" sound awfully military in Latin (pusillo animo?).
I started reading (though have not finished) the Latin Harry Potter and the Philosopher's Stone this summer; there are some great neo-Latin phrases in there, including citrina fervescens ("little fizzing lemon") for "lemon drop" (or "sherbet lemon"). And after that first chapter, you definitely know the words for "drill" (terebra, from terere, "to wear down," from which we get the word "detritus"****) and "cloak" (pallium, straight from the language). There was also some clever way to convey "flying motorbike," but I can't remember what it is.
*(Or, well, few children. You think of Montaigne being raised to speak Latin, and John Stuart Mill having Greek from age 3, and you start to wonder if there are any toddling classicists out there still.)
**Harold Bloom's case notwithstanding.
***Always in the third person, as ridiculed famously in the Astérix cartoons: