you're right Deino,
Besides I just don't think the Chinese want a Vtol fighter right now, They really Don't have a need just yet. Nato pushed the concept as they were worried about Russian forces bombing runways and needing to operate in bunkers and makeshift air bases built from highway tunnels. The PRC is not in that kind of mode to need to think about that yet.
So if we eliminate the Vtol argument. what reason is there to need a single engine?
F16 is single engine to reduce costs compared to the YF17 if flew against. Event today If you compare it to it's global rivals the F16 vs the Mig 29, although both have impressive lists units built of F16 smokes Mig 29. on the other hand A twin engine gives you more thrust, greater lifting capacity and generally a redundancy of emergency engine.
Navies tend to prefer twin engine fighters but that is just a preference not a law set in stone.
Air forces by contrast are happy either way.
Personally If this single engine is real I think it might have been created as a competitor to the Shenyang. and I would love to see a open fly off of both machines.