i read the three-body problem in chinese, but didn't read the translation. my impression was that liu cixin's writing isn't very literary - he rarely uses rhetorical flourishes or idiomatic expressions, and his vocabulary is very simple outside of technical language. however, it's very straightforward and accessible.
someone else i know described the novel as 'clearly written by an engineer rather than a humanities student,' and i think i'd agree with that description.
Engineers and scientists can be like that. Perhaps the most obvious English-language one is Andy Weir (The Martian, etc) where the characters can feel like they're agents implementing an story rather than part of it. But certainly author-first authors can lean into this too and end up writing basically a narrative report rather then a story.
Which is, to be clear, completely fine: sometimes the characters aren't actually the core of a story, especially when dealing with substantially non-human-scale subjects and abstract concepts. It's also much more of a challenge to keep characters front and centre when on a very large sci-fi stage. It's easy to concentrate on the people when it's just a few people in, say, a regular house, just doing human things. I think some of the genius of Iain M. Banks especially is that he manages to somehow place the people (and non-people like Ships) dead centre even though the stories are ostensibly on an incomprehensibly vast scale. It's one of the few sci-fi universes where I think first of the characters and not of the universe in which they exist.
The original Star Wars and Dune also had particularly good character-centrism, where the universes were clearly enormous and could be arbitrarily detailed, but existed to support the characters journeys rather then the reverse.
someone else i know described the novel as 'clearly written by an engineer rather than a humanities student,' and i think i'd agree with that description.