It seems a community module for v7 that allow to handle multilingual chart of account does exist : https://www.odoo.com/apps/7.0/l10n_be_coa_multilang/

By the way i can't install it...

But what about the Saas version? How to handle that with the officials modules/applications?

So the point of this is to be able ton install Belgium accouting (with PCMN) and have all the accounts (view/account) in both french and dutch.