In my opinion it is actually safer to bring the setup you are used to even if it theoretically might be less optimal on the other side of the road. Such a difference is very small. Sometimes you have to indicate to the left and sometimes to the right anyway.
When I lived in the UK for 2 years I had problems getting used to the reversed brakes and I was more or less only able to brake with both levers in the same way. I would suggest to bring your own bike instead if you do not remain in the new place for very long.
As far as I know there are no legal requirements to which brake is which. The bicycle just needs to have the brakes it is required (often two independent brakes, some countries or states may allow just one).