Russia gained a 'treasure trove' of intelligence on the US's best fighter jets in Syria

Well, that's the price you pay for actually using new technology, i.e. the cost of doing business. Since Russians pretty much used platforms we were fully aware of we may learned a bit on their newest tactics, but not much that we didn't already know about the platforms.

The only way they can find out about them without paying someone to steal information on them.

Hopefully, it scared the crap out of them.