Oh, being multi-lingual myself, I know that translating your writing from one language to another can be absolutely hellish.
Which is why I don't do it. Ever.
If I'm setting out to entertain two audiences that speak different languages, I'd write two separate versions. The two would, naturally, share the same plot/characters and such, but the wording simply wouldn't be the same, because there are certain things that will never make the transition without suffering major damage (idioms, for one).
