I discussed this passage extensively back in 2007 here:
I reserve the right to recant some of what I said there, but we agree that Shade must have had Hazel in mind when he wrote the passage. It's an odd choice, no? Why recast your dead daughter as someone else's dead wife? By turning Hazel into mere poetic material, doesn't he cheapen the grief he's established in Canto Two? I like your use of "mash-up," which of course describes not just this passage but the whole novel.
Let me share one very tenuous connection to this passage, which may or may not be valid. In 1959, just as VN was preparing to write PF, Mary Shelley's suppressed novel Mathilda was published for the first time, in an edition edited by Elizabeth Nitchie. The edition includes parts of a previous draft, a framing device (later abandoned) set in the Elysian Gardens (classical architecture and a fountain in the middle). Here we find souls "who having just escaped from care & pain have not yet recovered full sense of enjoyment," which seems likewise to be the case for the two wives in Shade's scene. Observing a group of "disciples" gathered under the fountain, the narrator is drawn to "a woman of about 23 years of age [Hazel's age when she died] in the full enjoyment of the most exquisite beauty [opposite of Hazel], her golden hair [like the wives in Shade's scene] floated in ringlets on her shoulders--her hazle eyes were shaded by heavy lids [hazle...shade] . . . But she appeared thoughtful and unhappy [again like the two wives]." Could this be the inspiration for Shade's scene?
This woman turns out to be Matilda, and her narration makes up the novel proper. Later in the Elysian scene, she tells of how on Earth "My passions were there my all to me and the hopeless misery that possessed me shut all love & all images of beauty from my soul--Nature was to me as the blackest night & if rays of loveliness ever strayed into my darkness it was only to draw bitter tears of hopeless anguish from my eyes [like Hazel's pained smiles?]." Matilda, like John Shade, was raised by her aunt (her mother died in childbirth and her father, heartbroken, abandoned her because she reminded him of his loss). When her father returns, Matilda is about the age of her mother when she died, and of course she looks just like her, so the father falls in love with her [see Catskin and many other incest tales], can't bear it, and commits suicide by throwing himself off a cliff into the sea. Matilda never recovers and ends up wandering the countryside, exposed to wind and rain, and dies of the illness brought on by the exposure. Leading up to her death, she is joyful because "I shall be with my father." Another quote:
"You [her one friend, Woodville], never regarded me as one of this world, but rather as a being, who for some penance was sent from the Kingdom of Shadows; and she passed a few days weeping on the earth and longing to return to her native soil." [Compare to description of Hazel in lines 337-356.]
And finally: "I go from this world where he is no longer and soon I shall meet him in another" (which reminds me, in a reversed way, of Hazel's appearance as the Red Admiral--replacing her mother, Sybil--as Shade's life, or personality, is about to run out).
Wish I could say something about the earrings and the emerald case, but I haven't made that connection. Sloughed cicada cases, by the way, do not retain the emerald coloring of the live cicada; all the ones I have seen are dull gray.