Perhaps you know about the A/C development cycle or not, I'm pretty sure you don't but the matter of the fact is that all genuinely designed system go through evolution which is called development cycle. It is an iterative process and even F-35 when through the same cycle despite billions of dollars budget, a multination JV got late many times.. First prototype of J-31 flew many years ago and since then China has made a lot of strides and the recent version has improved a lot so your info is not up to date.
By the way, a true 5th gen A/C can easily establish its air superiority above all 4, 4.5, 4+++ gen A/C easily as demonstrated by F35 in Red Flag exercise by achieving a 15:1 kill ratio over F-16V. Remember that F-35 is slower than F16 but due to stealth and far advanced modern technologies (most modern avionics and sensor fusion), it has a huge advantage over all other previous fighters including Grippen E, Rafale, EFT, Su35 or J16.
As far as F22 is concerned, it was designed around total air-dominance and not just air superiority.. however its extremely high costs ( per unit and operational) have resulted in closing down of its production line. USAF has around 150 F22.
However F-35 has more advanced aerodynamics than F22 due to more advanced computational power available to the designers for simultaneous calculations of the most optimal configuration for stealth and superior aerodynamic design. However F-22 is a twin engine A/C that has extra power and due to supercooled exhaust for supercruise and stealth, it has to produce enormous amount of thrust and thus it s a fuel guzzler. F-35, on the other hand, is slightly underpowered due to single engine configuration but it will be far cheaper to operate than F-22.
It is widely believed that J-31 is based on stolen tech from JSF (F-35) project. However since China didn't had a very powerful single engine so they opted for a twin engine configuration which gave it more P/W and thus higher speed than F-35. However it remains to be seen how the avionics of J-31 performs vis-a-vis F-35.