Your people have not come out in the open about the details as much as the Russians, Americans and even Indians are.
So the whole analysis revolves around what is visible or known with certainty.
For example, the shaping, stealth and aerodynamics.
I agree canards on their own are not too much of a trouble but there are caveats to that. The canards won't cause trouble from the front aspect. The problem for you is that the Radar and IRSTs are all volume search capable. They will seek out the same kind of range in all directions. OTOH the plane simply has to manage its best LO aspect (frontal). From other sides no LO/VLO plane is going to be as stealthy as the brochure and forum talk admit.
Then your people compromised again by putting those ventral strakes/fins. That by itself acts as a nice radar reflector from the side. Your pilots will have decide if they want to hide those strakes if the radar is flanking the planes. And if he tries to hide the strakes he either ends up changing course or may be show up a different corner reflector with its canted stabilizers. I don't know how desperate a need those strakes were. Your J-31 doesn't have those, AMCA won't either, none of the already flying 5th Gen planes do. But J-20 does. Everybody is trying desperately to reduce the number of control surfaces. The J-20 engineers instead increase them. Who puts in so many control surfaces all at different angles in a supposedly stealthy plane.
Same is the case of canards. Su-30MKI has them but only as a stop gap measure. The Su-35S made improvements in power, FBW, TWR and TVC and as a result are able to drop canards altogether. Now true the J-20 canards will not be a problem if the frontal aspect is presented but then in real world missions it is going to use them and those wings and canards with edges at two different levels will cause an unpredictable reflection.
In general there is little attention to conformal stealth in J-20. The radar waves will be reflected away, I agree, but in several different planes. Ideal for Bistatic/Multistatic detection.
I am sorry but a J-20 is going to be LO only in the attack mode. That may sound too kung-fu-ishly hexy but that is crazy.
The counter LO/VLO tactics for SAMs is to approach their target in a "doglegged" trajectory such that the onboard sensors can get the biggest billboard or the side view of the targeted LO aircraft. This is by now a well understood concept of operations. But if its a good Conops for SAMs with their piddly little sensors then what would you say about a whole aircraft with 4/6 AAMs using the same tactic. Should your people send in the J-20 over the Himalayas to try to establish air superiority, I will just have to send in LCAs with from 2/3 different vectors, all launched from the Advanced Landing Grounds. Quick Reaction and difficult to manage pack of Dingos.
In fact I am much more afraid of your J-10s. Because they too can sort of do what the LCA does. Most likely the J-20s will end up so expensive that your people will field them opposite the Taiwan Straits, against carrier led aircrafts, which coincidently don't have the right kinematics or even aerodynamics in some cases, to take on the J-20, unlike the LCA. And a pack of LCAs backed up by an L-Band FGFA with easy access to several bases, will be simply impossible to handle.
You are right some of the people here are cussing J-20 only because they love the JSF too much or perhaps they don't know how to understand / react to the J-20 simpliciter. The trouble for them is that J-20 has more than enough volume (something we have learnt to respect the hard way) to host a lot of future tech. J-20 may end up outfoxing the JSF in the Strike missions and do that comprehensively while also sporting more than a significant edge in air-to-air combat. As I often say - there is a second mover advantage too. You don't have to repeat the other guy's mistakes. Americans made their JSF too small to be good for anything. They ideally should have persisted with F-22 iterations. Bad choice.
J-31 looks more like a - made for Pakistan 5th Gen. No access to esoteric and expensive gizmos. Not much room for growth. Defensive plane.
Hope your people standardize around J-10s and J-20s at the earliest. It will force our people, to up their game, as well.