Who was Rará?

Cortázar's short story "Carta a una señorita en París" (Letter to a Young Lady in Paris) is narrated by a man who has a peculiar propensity to spontaneously regurgitating a baby rabbit from time to time. A little musicological puzzle has popped up in it. In the first paragraph, the narrator moves into a borrowed Buenos Aires apartment, where he is reluctant to disturb (though he will) its "closed order, constructed even in the finest networks of air, networks that in your house preserve the music of lavender, the fluttering of a powder puff, the interplay of the violin and viola in the 'cuarteto de Rará'," whatever that last phrase may refer to. That's my rough translation; the word translated as "powder puff" is cisne, which literally means "swan," hence the "fluttering." Paul Blackburn's version, published in End of The Game and Other Stories, reads as follows:

... it offends me to intrude on a compact order, built even to the finest nets of air, networks that in your environment conserve the music in the lavender, the heavy fluff of the powder puff in the talcum, the play between the violin and the viola in Ravel’s quartet.

Ravel? Why Ravel? For that matter, what was the "Rará quartet" or the "quartet by Rará" alluded to in the original. The allusion has baffled several commentators ("I have obtained no reference to this musical piece, if it exists" — Descifrando a Cortázar), and only one critic seems to have hazarded an explanation. Monica Kanne, in her thesis Estrategias de la traducción: Un estudio de estrategias de traducción y su aplicación práctica glosses it as "una pieza musical (del año 1949) del compositor italiano de música clásica contemporánea Sylvano Busotti (1931-)," that is, "a musical piece (from 1949) by the contemporary Italian classical music composer Sylvano Busotti" (actually Sylvano Bussotti, who has since died).

At first glance, this seems plausible. Although I haven't been able to trace a Rara Quartet by Bussotti, he did compose a Rara Requiem and direct an art film entitled Rara. He would have been only in his teens when Cortázar's story was first published (in his collection Bestiario) in 1951, but he was in fact precocious; the IRCAM database of contemporary music lists compositions as early as 1937 (when he was six!), though I find no record of an early string quartet. Still, it's a bit of a stretch that Cortázar, living in Buenos Aires at that time, would have had any exposure to the work of a teenaged Italian composer. As it happens, though, there's a simpler explanation: Blackburn's translation is correct, because "Rara" was a nickname of Maurice Ravel. (Per biographer Benjamin Ivry, "Ravel was known in his own circle as Rara.") Blackburn may have known that already, or Cortázar may have explained the reference (the two conducted a long correspondence). Author or translator or editor (or all three) decided that the allusion was too obscure and clarified it. Ravel's String Quartet in F Major is easy enough to find:

There are even excerpts of a version for ondes Martentot, a kind of precursor of the theremin: