Uspensky does comment on the dialogue structure in the Song of Songs in relation to provenance. Ascribing text to certain speakers is interpretive, and (for Uspensky) shows that the origin of the Codex is from outside the Church.
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Good to know and a good way to put it.
Although Uspensky has a lot in his first book 1856, on Song of Songs, this provenance note may be in the one you are translating from 1862.
Tischendorf even comments on the Uspensky provenance position in:
Vorvorte zur Sinaitischen Bibelhandschrift zu St. Petersburg, (1862)
Footnote on p. 15
https://books.google.com/books?id=T-BUAAAAcAAJ&pg=PA15
Ending with --
".... According to him, the text of the New Testament is of a special kind, perhaps derived from private use or perhaps from the catechetical school of Alexandria; but at the same time it had been corrigated according to the general text of the orthodox church. For this reason he attaches a special value to the manuscript, as he testifies that the text of the church has been the same at all times."
This is also the spot where he tries to address the Euthalian cola et commata issue raised by Uspensky. Which is quite fascinating as well.
And possibly there is a bit in:
** Die Anfechtungen der Sinai-Bibel
However, I did not pull out any such notes from there.
Afaik, neither Tischendorf or Uspensky comments on the unusual sophistication in its own right, which includes the rubrications. And I don't think this issue got picked up by Hilgenfeld or others, except one writer in the English Journals, Benjamin Harris Cowper (1822-1904) (quite astute). And I do have those urls and quotes available. And I think, from memory, that I came upon a new auxiliary quote on the same topic the other day, so I presumed for now that it was also Cowper.
Jay Curry Treat in 'Lost Keys' defacto shows that this came out of a later Latin medieval interpretative schema. (Treat is unable to give that interpretation because of Sinaiticus 4th century presuppositionalism. However, it is an incredible read.)