Agreed, if PAC wants, they can surely go a "Gripen Route". However, the devil is in the details here.
Using Spanish EW in a basic EW suite is fine but when you move to current high end EW tech, it requires very close integration. The Chinese won't allow that kind of integration with their systems, as it would allow Western companies to get details.
For instance, it is perfectly technically possible to integrate AMRAAMs on the JF-17. All you need is a handshake between the Chinese radar, JF-17 electronics and the AMRAAM. However, this cannot be done.
Now imagine your RWR, other sensors, EW on pods, radar, all seemlessly needing to talk to each other instantaneously. Yes, if a system from Spain allows itself to be given with full access to the source codes, it is possible to integrate it. However, when you go into higher end systems, like those on the Gripen, the Europeans would:
1. Not sell
2. Sell without full access to the software
This means that seamless integration is difficult at best. Meaning that instantaneous and unified working of the electronics is now not possible.
Again, the Indians made this mistake. Israeli equipment was not able to effectively integrate with Russian equipment. Not because the Indian engineers were incompetent, but because the Israelis and Russians didn't want to give each other access and insight into their systems. Had the Indians not been short sighted, they would have never gone through to begin with.
And that was for tech 2 decades ago. Last generation EW. The problem becomes 10x with the current generation of EW. Let me explain this further. In the very latest technology, your radar itself becomes almost a subsystem of the wider EW system. They need to seemlessly work with your EW pods, RWR, DRFM, processing, etc at the fastest, most instantaneous way possible. If it can't do it near instantaneously, the whole thing collapses in terms of its effectiveness.
Gone are the days of brute Russian jamming. Yes, that still works, but the art is far more refined to be as efficient as possible, so that small aircraft like the Gripen can have a meaningful EW capability.
The American F/A-18 Growler combines both brute power with ultra refinement. This is what makes it such a major asset. Meanwhile, the F-35 does ultra refinement. It is claimed that DEW is now in its capability - but this may be urban legend.
What does that mean? What is DEW? DEW is the ability of an EW suite to do permanent damage on an enemy system. A radar, for instance, is a powerful microwave. If you walk in front of a radar, you are basically getting an x ray and if you have chocolates with you, they will melt. A very powerful microwave directed, pinpointed at a point, could cause permanent damage even to the enemy system. "Fry the electronics".
Now imagine a generation even beyond that - something perhaps we may see in the near future. A laser and the radar pointing their energy at an enemy aircraft's radar, RWR, and perhaps frying those electronics. That is the future.
To complement this brute power, you have a very effective DRFM and processing that allows you to instantly jam and algorithms that allow you to anticipate what the enemy EW will do. So you can now put your whole jamming capability into the small band that the enemy radar is about to radiate.