PAF has this in pipeline for few years maybe paid in pieces. Secondly Chinese have given use these for cheap and most importantly this batch was meant for PLAAF but PAF took it all thanks to China.
Pakistan has ability to track each and everything inside Pakistan and to an extent outside too. Even the stealth fighter with induction of new jet.
Pakistan has been building up it's SAM inventory and FD2000 will be inducted soon. Unlike india we have eagle eye view of things in our airspace...