Books like The Borrowers Avenged

I think that Mary Norton just lost it by this point. Great borrower hijinks, fun descriptions and imagery, and then a seriously bonkers literary structure. Ghosts are set up quite deliberately and then never actually enter the plot. Why are there the horrifying ghosts of a murder-suicide in the middle of a nominally children's book?Spiller and Peagreen are set up as romantic rivals for Arietty, but the foreshadowed tension never even arrives, let alone resolves by the end of the series. We spend the first half of the book (even more than usual!) establishing a plot line around humans and avenging the borrowers. That is then abandoned until some half-assed wrapup in the last few mini-chapters.Not a spectacular finish for a series that was otherwise fantastic.