That's weird. Must be some new style of titling chapters that I haven't heard of. I don't really frequent the kind of blogs that would have informed me of it. (If such blogs exist.) Thanks for bringing it to my attention.

Wanderer Between Worlds, the list you have given seems consistent if you follow these rules:
Any personal name (human or beast), name of a building (Witch's House), name of a foodstuff (Turkish Delight), significant thing (Deep Magic, White Stag, Dawn of Time), should be capitalised in a title.
Other words in the title should not be capitalised.
It was always usual to capitalise all words in a title, or else all but the small words (and, the, to, in, etc).

So, I could have sworn that the official title of LWW is all capitalised, thus The Lion The Witch And The Wardrobe. So I dug out a copy or two.

But it isn't - the facsimile of the first edition has all capitals ('and the' smaller)THE LION, THE WITCH, AND THE WARDROBE, on the spine, then THE LION, THE WITCH and THE WARDROBE on the front. The chapter headings are all smaller capitals, and the word 'BEFORE' is italicised in 'BEFORE THE DAWN OF TIME'.

By the 1973 Puffin copy, which was my first set, the spine has block capitals on the spine, fancy italics on the front: The Lion, the Witch & the Wardrobe, and Italicised chapter headings as you listed.

Harper Collins was publishing by 2000 when my large hardback copy has: all capitals on the spine with larger capitals for The, Lion, Witch, Wardrobe and capitalised words on the front cover (except 'the' & 'and the'). The chapter headings are similar to your list, but 'dawn' has no capital ('the dawn of Time').

My guess is that the editors/publishers decided that children should have ordinary writing in chapter headings as much as possible.

Any personal name (human or beast), name of a building (Witch's House), name of a foodstuff (Turkish Delight), significant thing (Deep Magic, White Stag, Dawn of Time), should be capitalised in a title.
Other words in the title should not be capitalised.
It was always usual to capitalise all words in a title, or else all but the small words (and, the, to, in, etc).

It sounds about right, at least within the book, to emphasize in chapter headings significant bits of the story. The covers are often a whole new kettle of fish, to be appealing to the casual shopper or reader. Besides, did Harper Collins in producing these copies, consult Library of Congress rules about titles, the ones we were expected to follow in libraries? Titles in a bibliography only have to be capitalised by the initial letter in the title. Unless there is in that title, a proper name, a place name (eg Narnia), or particular times & months of the year, eg (The February dragon, The real Easter Bunny, or, Deborah Cadbury's Easter bunnies for all chocolate-lovers), usual capitalisation rules & practice also apply. That includes adjectives indicating nationality as well.

If someone is called The Witch (ie Jadis) yes it should be capitalised. Same with The Lion (ie Aslan), but not necessarily the wardrobe, since until you read the story at first appearance it is just any old wardrobe, however unique as it turns out to be. A chapter title might well be Turkish Delight within LLW, but if Deborah Cadbury was writing a book about how Fry's Turkish delight became incorporated into Cadbury's Easter eggs, you might find a chapter heading capitalised quite differently. Similarly, even if I was writing a book about Jadis, I would be more inclined to say The White Witch's house, or The Witch's house.

When chapter titles are applicable they very often are all in block letters, anyway, so there isn't a noticeable problem, & it may well be the convention inside a book to capitalise more significant items & buildings as well. Meanwhile, I wouldn't get into a stew about it, let alone a witch's cauldron. You can get into enough "double, double, toil & trouble" with such niceties even when it is part of working life. Do enjoy your nice unique copy of The Narnia Chronicles meanwhile.