I have built a few Chinese frames. The best one I’ve used is DengFu R02… I don’t have it any more but I know the person who does and he still rides it hard and loves it. The only one I’ve had a problem with is a Yoeleo frame. The bottom bracket shell was crooked in the frame. I had built a couple others of theirs with no problem. I contacted them and they sent me a replacement. Told me to keep the frame. I still have it but it’s pretty much useless. I want to try my hand at painting frames sometime so I’m just holding onto it for that purpose.
I am not a fan of the Chinese copies of other brands. But a friend has a Chinese “Bianchi” with Chinese “FFWD” wheels. I’m honestly impressed with it. I helped him build it and it went together nicely. It’s too small for me so I have only really ridden it around the block, but he has put a lot of miles on it and there is no issue with the frame or the wheels. I’ve never ridden a real XR4 so I can’t compare them. But honestly aside from this being a knockoff it’s a fine bike. I’m not encouraging anyone to buy a knockoff though.
The one thing I’d suggest though is if you go with a Chinese carbon frame, go with a rim brake version. I have seen more than a couple disc forks fail under heavy braking.