I am struggling to trace some of Burnet’s citation in his apparatus criticus. He cites Ficino/Ficinus on 29d1, 37c10, 52c5, 56a5, 60d8.
Assuming that Burnet did not use manuscripts, did he use the 1484 Latin translation? But since he quotes Greek words, I assume it might be Ficino’s 1496 commentary? But which print might he have used (given that there was no critical edition of Ficino’s Philebus-commentary in 1901)?
I was going to suggest you tried asking Michael Allen, who was a colleague of mine at UCLA, but he died two years ago.
Another line of approach would be to contact the prospective editors of the new OCT. Unfortunately that stalled after the publication of the first volume 30 years ago! (I reviewed it in BMCR.)
Your query is an extremely recondite one, and it astounds me that your previous one attracted so much attention here, on a site which is otherwise practically dead.
After having surveyed some earlier editions from the 19th century, as well as reprints of Ficino’s translation and commentary, I now believe that Ficino did not annotate Greek variants in his commentary/translation. His focus was on philosophical exegesis, not textual criticism. Thus, following editors (beginning with Cornarius) had to extrapolate from Ficino’s Latin choices what Greek he must or might have read.
Coming way late to this post… Burnet had access to a 1539 edition of Ficino’s Platonis Opera in the St Andrews University library, and, if he wanted, a 1517 edition in Edinburgh. But in any case I doubt he was doing much if any original examination of editions of Ficino’s translation (or Philebus commentary), instead taking his cue from Friedrich Ast (29d1), Gottfried Stallbaum (37c10 (through Janus Cornarius), 52c5), Philip van Heusde (56a5, though Burnet doesn’t make the connection explicit in his app. crit.), and Immanuel Bekker (60d8). He could have consulted the translation in, e.g., the Bipontine Plato. Likewise Burnet, who worked fast (he published the five volumes of his Plato OCT between 1900 and 1908, though the Praefatio of vol. 5 is dated 1906), relied heavily on the collations and reports of others (Bekker, Stallbaum, Martin Schanz, Josef Král, some others), often to his cost. No criticism of Burnet here, who is rightly characterized by Simon Slings as “facile princeps” among editors of Plato (in Slings’s preface to his Republic OCT). But assumptions about the job of editor were far different 125 years ago, for many good reasons.