Outdated copium TBH. PRC engine programs going smooth last 10 years, doing their on variable bypass programs as well.

Turbojet/fan core programs bottle neck isn't technical, its political / organizational, assuming some base pop scale, i.e. need to sustain specialized aerospace workforce of a few 100k which most countries can not - and EU has to as bloc - but trivial for PRC. What's hard is building the entire process / development pipeline etcs. Tremendously expensive and takes political will to sustain, with little expectation of returns, over 10-20 years. This was last piece PRC was building out post 00s, which basically caught up ~50 years in ~10 years for military hot section... aka one should expect rapid catchup in civil aviation if PRC serious. As if PRC not good at parallel iterations and tacit knowledge buildup at PRC scale. But IMO civil aviation not PRC serious/priority, nothing that increase reliance on fossil is.

The other caveat is commercial aviation is deeply geopolitical, PRC can very well have competitive engines and still have difficulty commercializing because west currently has chokehold on regulatory/certification. Half the reason COMAC went with western components is due to ease of certification, really if PRC wanted right now, they can plug Y20 avionics / components into domestic narrow/wide body (turbojet not 1:1 price/perf swamp with turbofan) but the point is PRC at point where if they wanted completely indigenize domestic civil aviation with eye on medium/long term global expansion, they could.

Other thing to consider is "commercial" viability of jet engines is pegged to oil price, i.e. aviation fuel opex at current prices means marginally more performant engines (5-10% better fuel efficiency) will economically pay themselves off over lifespan at recent fuel prices. If aviation fuels dips to historically precedented lows, PRC ability to involute component prices to commodity levels can become competitive, i.e. the economics of spares/maintenance of having lower priced hulls > fuel price.

But ultimately, formula for frontier capabilities is basically having industrial policy that can eat a lot of losses during incubation while generating/coordinating the required talent.