Both J-20 and J-15 are frontline fighters. I doubt you can get any frontline fighters without "spending billions." Chief designer of J-20 is Yang Wei and he is now President of China Aeronautical Society.
Both Yang being fired and the J-15 as "shit" are both Indian wishful thinking
With Type 003 and its catapults, the J-15 will be among, if not the highest load carrying carrier aircraft ever with 8000kg load (it is a flanker after all!)
The J-15 had landed hundreds of times on the Liaoning and Shandong. There are only a handful of aircraft that can land on a carrier anywhere. Seems pretty successful to me. lol
I'm sorry, but it is just wishful thinking that a country that builds carriers and destroyers by the dozen would somehow build deficient planes and missiles by the hundreds and thousands
Again, poor performing systems have very limited production runs -- like two or three for ships or a handful for aircraft.