In my venerable Soncino translation, actually dated 1934, the author of this section has a very interesting discussion on the term 'matnita' referring to the Baraita at the end of 9b, suggesting that this is the only reference in the gemarra to our present day 5770 counting. Not only that, he comments on a number of manuscripts that scholars concluded were actually forgeries, trying to establish various dates for when our current practice became widely accepted. He concludes that it was probably in Germany and France 12th-14th centuries - rather than Spain. In other words, though the Baraita suggests that the rabbanim of the gemarra were well aware of this, it seems to have been 'forgotten' or 'overlooked' for many centuries before being revived and coming into general acceptance. Any comments?
Dr Joseph Berger, Toronto Canada