Agreed, but what makes me suspicious are these two IMO contradicting statements that (1) few peoples already had the "previlege" to have a close look up to a WS-15 but (2) also that only few people did realize it as a new engine.
Also it was said, that the nozzles not only differ by numbers but also by shape... so are these guys/peoples bad in recognising such major differences?
That sounds like a more reasonable explanation than the idea that JJ20 had already been flying with WS-15, tbh