Formal vs Casual l10n
In most languages a question arises as how to translate English: should the translation be in a formal or a casual style?
Well, b2evo is moving towards a profesionnal content management system more and more, so the answer would definitely be rather formal. (If you'd prefer a blog toy instead, there's plenty of them available on the Internet, though ;D)
One thing you could do is check out how applications like Microsoft Word are localized. You should use similar style.
Anyway, when in doubt, please use the formal style.
Thanks for your help!