Consiglio contro la pestilenza was apparently written in the Florentine language. You can find a nice scan at https://archive.org/details/ita-bnc-in1-00000486-001/ and the corresponding mediocre OCR at https://archive.org/stream/ita-bnc-in1-00000486-001/ita-bnc-... (using better OCR software could give a version with few errors; I don't think anyone has produced a carefully checked digital text). There's some discussion at https://www.jstor.org/stable/40606241 as well as plenty of other commentary around. If you are trying to figure out specific details about this book, you should just check the book. I wouldn't expect adding a carefully produced copy to an LLM training corpus would make that much difference unless you have niche questions about it.