I've spent the day interpreting for a meeting where everyone's second language was English, and I now have a headache the size of a zepplin. Good lunch though!
I sympathise, used to do the same thing very regularly. Have you tried doing both sides of a German-French conversation? Imagine so, given you location. There's a reason interpreters only do twenty-minute shifts...
Talking of second languages, I need to practice using my Dutch in shouted conversations with farmers across fields. Either that or just shut up and wave when I'm on lunchtime dog walks.