Can I send a query to agents in non-English speaking country and translated version to agents in English country at the same time? I assume I have to inform them about this upfront. How it will affect my foreign rights in potential publishers' deals? Would it be better to focus on one country and then settle that with publisher?
Like Robjarvis said, it is about money...
When you meet with a publisher they will automatically try to take your foreign rights in the contract unless you demand them. They make money for an outright sale to companies all over the globe and the overseas companies own the intellectual property that should be yours.