When people are influenced by Tolkien, they write homage. When people are influenced by Lewis, they write critique.
There's an entire Harold Bloom Anxiety of Influence thing to be written about the need to rework one's relationship with Narnia as one grows up and needs to deal with complicated feelings about Narnia as a place.
I'm not in the mood to write it, but it definitely exists and it's attempting to negotiate the Christianity, the simplistic portrayal of women, the "problem of Susan" and what exactly this strange place that exists to gratify the whims of children is...
And, I mean, that most of what Tchaikovsky is doing here: exorcising Lewis. I'm not entirely convinced it works as a book, but Tchaikovsky has always been a writer of ideas through story rather than either character or narrative so that tracks.