The way China building new reactor is not typical.
Most of the countries builds _one_ type of reactor, or a group of similar type of reactor. This help reduce the cost of training and certification.
China, otoh, tries to _diversify_ their reactor type.
If you look closely on how China treat techs, they have been doing the same for all tech for past 15+ years. They are strategically growing their tech profile.
They also, most importantly, don’t have to care if any of their reactors make economic sense. It is a single party state, and the incentive structure is very different.
most of chinese units are hualongs now
They have a huge number of people that can specialize in many different things.
But their government has actually explained it. They purposely diversify any tech that doesn't have a clear winner, so in the long term a winner appears and they can focus on it.