Some of us are old enough to have seen three or four generations of Russian aircraft cause the sky to start falling on our heads.
The biggest "scare" of them all was the Mig-25 scare. Remember that scare? It was this super fighter that was going to cause the end of days for America and her allies. And the thing turned out to be, at least the early versions, to be a piece of junk. By that time we had started training our bomber crews to fly NOE and it turned out the 25 had a useless radar for finding anything flying 500' or under. Sure it was fast but what good is "fast" when thats all you have? Then some Russkie decided he liked Capitolism more and flew one of the things to Japan where we got to take it apart. It turned out the Russians do pretty well with what resources they have, and we already knew that, but the MIG-25 was not a good enough reason to notch up our development even more. But it was the cold war and we did anyway, ending up with the F-15, 16, and F-14.
In the history of modern era Jets Yank legacy fighters have filled the sky with red when in combat against Russian aircraft. I'm sure the SU-30 is a fine legacy fighter/bomber. But IT IS a "legacy" fighter. Fancy air show dances mean about as much to air combat as did the Mig-25s speed records. In fact they mean very little.
And to judge a modern jet fighter you have to look at the system as a whole. The Jet itself, the avionics,the weapons, the supporting assets, the reliability of the engines, and the training of the Pilots. The reality is an SU-30 armed force, like Indonesia, would have a really bad time of it against an F-35 armed force like the RAAF. Most of all when you figure in the entire package the RAAF would throw at them.
And actually, to tell you the truth, I'm not sure the Russians themselves could do much better. Against an adversary like NATO I think the air war would be short, sharp, and painful for them.