We found out by analyzing recorded games and calculating resource gather rates. Furthermore, unit movements in tournament series showed signs of maphack - though this is much harder to prove. Our modders have identified these cheats and will patch them in the next version of EP as soon as possible. I'm sad to see things have gone this way, but I'm also glad that we managed to spot this in such an early stage of the tournament. Special thanks goes to @somppukunkku who tipped me about possible cheats and @EAGLEMUT who also analyzed the recorded games.
As I said, this was posted about 5 minutes after I was notified - something I'm not happy with as there are still lots of loose strings. We haven't decided what to do with the played series vs SomppuKunkku and ILeGiTBosSI, for example. Since the RO32 is already extended by one week, I think it'd be best if SomppuKunkku and ILeGiTBosSI both faced off for the RO16 seed if they're willing. That way, the community still gets to enjoy a good series. This hasn't been decided yet, but I will keep everyone updated.
Once again, my apologies to all viewers and donators, and thanks to everyone who values fair play as much as we do! Feel free to PM me if you still have any questions.