Part 2 of Oleg Interview - you can use Google translator from Russian to English or language of choice
http://www.spread-wings.ru
If you read the above article carefully. It indicates the source for IL2 has long ago been distributed among devs. Maybe some for money, maybe some for free, maybe just a way to wink and say NO at the same time.
Regardless, the source code is out there in internet-land and it's being used.
Oleg's statement in the above article included, "If you talk about some of the other developers, we have transferred them to the source code <IL2> a long time."
It is translated from Russian. I would say that Oleg knew what he was doing when he released the code.
The place to discuss mods is in the place you acquire them, not here.