> Is the surplus lost? Or traded 3:1? Or simply taken in account regardless of the 15 as maximum?
You can trade in the surplus at 3:1 or get stuff from the market right away. It specifially says that you can do this in the Scoring section of the rules (at least in the English rules).
Just for clarification:
1) What are you trading 3:1? I assume you trade the 3 extra Buffalo and get one more Wildfowl.
2) How do you get more from the market? We have played that if you have 3 extra Buffalo, you then have to give up 3 fish & 3 Wildfowl to get a 3 item from the market (or 3 1 items, etc).