No IAF is not "freely crossing" LOC.
It is as real as Pokémon running around in my bedroom.
SU-30 didn't cross because the pilots flying them were professionals not internet fanboys or BJP goons and knew that LY-80 are waiting for them on the other side.
You are confused about something. No, fighter jets aren't crossing the LoC, that would be foolish, especially from a diplomatic and political PoV. It's unarmed UAVs that are doing it, providing targeting coordinates to our artillery.
Su-30 not crossing the LoC has nothing to do with anything. As for LY-80, with the small number of batteries you have, none will be along the LoC.
Link-16 was used very successfully on 27th February, so there's the hint.
Sure. It's a proven datalink. But it doesn't change anything with respect to physics. X band is better than S band in this role. S band works really well at low ranges, like targeting provided by ships for point defence. At ranges above 50-75Km, good luck, you will need a gigantic radar. So against a target over 150Km, it's going to be quite useless. That's why I said the range advantage without a decent fighter jet radar will only give you a slight advantage over the AMRAAM that you already possess. At least you can be sure that the PL-15 will be superior to the AMRAAM.
There's the question of range based on the type of aircraft as well. Take the Mig-29UPG for example, the JF-17's AESA claims 170Km against a 5m2 target, but the Mig-29UPG has an RCS of 1m2. Similarly, M2000 is 0.8m2. LCA Mk1 is around 0.3m2. LCA Mk1A is below 0.1m2, along with Rafale.
So the JF-17's radar may only detect the Mig-29UPG at about 115Km, whereas Rafale will be picked up at as low as 50Km. At worst, 130Km for Mig-29UPG and 100Km for Rafale, with missiles. Without ECM. With ECM, the ranges will be even more degraded. The Erieye also will experience the same problem, although it most definitely has more range than most fighter jet radars, but will have crap resolution at such ranges.
Otoh, the Rafale can pick up a 3m2 target from at least 250Km away. So, even if the JF-17's RCS is considered to be 0.1m2, it will be detected at about 105Km. Once you add missiles to it, it will likely be detected at 170Km by the Rafale. The upgraded MKI will do even better than that, 170Km without missiles and 260Km with. So both jets will have a massive range advantage over the JF-17 Block III + PL-15, even if the Erieye supports it.