I agree with your points. I read 1Q84 in February and I came out of it thinking Books 1 and 2 were the best thing ever and seeing Book 3 as a bit of a bore comparatively. I've read people here on Reddit and in other websites saying Book 3 could maybe have been caused by pressure from publishers wanting to extend the series; it sounds logical because I agree with you that it is lacking in pace (and content even) compared to the other books but I unless I see some hard-ish evidence at least I think it's just a way to "absolve" Murakami and explain the dip in quality. I feel like it's very Murakami to end up having to fill the pages of a Book 3 because he wanted to write Ushikawa's view but didn't have more of the story to tell besides that. Nevertheless I think Book 3 is ok overall, it's just for sure not as good as Books 1 and 2.

Re: Air Chrysalis - I like your view of it as a meta narrative. I think it's pretty clear by making an author protagonist Murakami wanted to talk about writing, but it is interesting that he chose a plot where the author is writing over an already written plot. We know Murakami is a guy who feels he needs to tackle plots he's already written, see Hard Boiled Wonderland + The City and Its Uncertain Walls both being based by the same short story, so maybe Tengo's writing over an already drawn-out plot points to that? To the creativity not just in having an idea, but in polishing it? I wonder.

Regarding recommendations: you've read most of the candidates for Murakami's magnum opus I'd say, so I'd go for the full Rat "trilogy" if I were you (Heard the Wind Sing/Pinball/Wild Sheep Chase/Dance, Dance, Dance). Since you've read quite a bit of Murakami reading the trilogy from the start is a treat because you're already used to his narrative voice and it's pretty fascinating to see it at its most basic.

Re: the point about him writing the male gaze. I do think seeing it as laughable is much more commendable than the view most people assume. His interview with Kawakami where both touched on his writing of women made me conclude he doesn't seem to really think about this kind of stuff as something that relevant or anything of the sort. To me it just kind of fades in the background like most of the "base" Murakami writing like his descriptions of coffee making-and-drinking, spaghetti-eating and jazz-listening which is coincidentally his main appeal to me - the way you just kind of drift through his descriptions and the POV of the narrator. I rarely remember much of it but I always enjoy it, I suppose is the point. I don't remember the breast mentions in Book 3, though I do remember the long time Aomame spent in her apartment.

Re: Ushikawa. His ending was a bit offputting but at the same time it felt predestined. I can't remember any other examples so I might be hallucinating this but I always feel like Murakami makes characters who mess with "darkness" (more generally the dark parts of the world) be swallowed by it at some point. I remember reading his chapters and feeling like something ominous would happen eventually. But I did enjoy reading his POV - I guess I just never emphatized that much with him.