I haven't looked at the letter, but I think I would be very confused by this DNW. My normal writing style is fairly close to the style of many of the kinds of books I offer to write for, and trying to keep the characters in-character and the setting recognizable usually means I end up leaning even more into the style of whatever canon I'm writing. How will the characters even sound like themselves if I write them in some other style?

I think you may need to be more specific about what you don't like about pastiche, or what specific narrative style you're looking to avoid, because to me this DNW feels a bit like "DNW fic that resembles the canon." For a book fandom especially, the writing style can be a big part of what the canon *is.*