The sales people of any modding company is not important, they can be based anywhere.
The developer(s) the 'team', which you might thing might be 10 peple, 5, people, is usually 1 or 2. They are mostly kept secret.
People are so confident that they are in europe, but the guy could be living next door to you - you never really know. You don't need to be apart of production to make software. All you need is a PC, and a DS.