We probably won't know the precise figures for a long time.
But we can be pretty sure that China has come a very long way in military aircraft engines. The progress is across the board and foundational. That is, they have made strides in design, materials and gained tremendous operating experiences, given how many WS-10s have been produced and in service by now. A lot of things about aircraft engines are still empirical and experience-based. As the article said, Taihang or WS-10 has been 40 years under development and iterations. I still recall that sense of hopelessness about WS-10 and Chinese aircraft engines in general back around 2010. It feels quite differently these days.
So, even if much of the article is speculative and based on indirect evidence, the trajectory of the development is more or less credible.