Two Stars out of Five.
Non-steam steampunk? Jules Verne, almost by definition, invented steampunk. I believe Valtat calls his genre Teslapunk perhaps because so much depends on early and revolutionary use of electricity.
Would it be too gauche to suggest that the emperor has no clothes? Valtat is an award-winning French science fiction author. This story, written in English, is praised by all the right and right-minded people, but all I can think is “I can’t believe I read the whole thing.” Did they?
Undoubtedly Valtat had fun twisting the words and ideas. If he couldn’t find an obscure word or alliteration, he invented one. The plots are lost among the world building until last hundred pages. Many readers won’t survive the frozen first hundred. The principal antagonists’ inner voices sound alike. You can only tell them apart because one was always indulging in this or that drug or sexual liaison. No point in identifying technical errors; it’s all fantasy.
Quibble: Does Valtat realize that at longitude 90 degrees north, latitude becomes irrelevant?
Why not one star? Because it is a great concept. And Valtat has his funny moments. Some people apparently like it. But they probably insist the emperor was clothed.