I currently have two languages set up; English and Dutch. The only difference is in keyboard input. The Dutch one uses the French/Belgian AZERTY layout and the English one uses the Irish/English QWERTY layout (
When a Belgian colleague needs to use my computer, I switch the language to NL (Dutch) (therefore the input to AZERTY) using the language bar, but it seems to be application-specific. (I.e: After changing the input to AZERTY for my colleague, if he then clicks on another program it switches back to QWERTY for that program).