I know the last post on this one was in March, but I thought I'd throw this out there anyways... a la Fellfrosch, it's not only correct usage in Mexico, but would be understood properly pretty much anywhere.
There's two reasons why, both revolving around the fact that it indeed
doesn't read:
"The most beautiful fantasy novel that will be written in many years."
First, though escribirá is future tense (hence "will write"), se escribirá is
not future tense, it's reflexive. It's not a concept easy to explain in English, but to a native Spanish speaker, it makes a lot of sense. A serviceable somewhat direct translation might be "to be written" - I honestly don't know offhand what the original quote in English was, mind you. A proper use of reflexive tense - in this sense of usage, since there are others - could be taken as present tense or future tense, depending on the situation.
Second, this wasn't a direct translation, it's a concept translation poked into a direct translation. The first is useless without the second thrown in... to give an easily understood example why, try directly translating jokes word-for-word, literally, from Spanish to English. It just doesn't work. But translate the concept into something intelligible, and voila! you just might make someone laugh.
Which brings up a suggestion for anyone getting something translated... it
really pays to not only get a good translator, but getting the translation through at the very least a few good native speakers before stamping your approval on it. I've seen books fail in Spanish, for example, that really shouldn't have... I just don't think as much attention was paid to the translation process as the original publishing process.
Whew... that said, I hope Elantris didn't suffer from translation, and I really hope Mistborn doesn't!