Concerning the 1st day of Tishri, yes, it was the New Year start of an exceptional 50th year in the original Hebrew calendar. (Leviticus 25:8-10) But it also seems to have been a reference point for yet another astronomical synchronism. A mysterious number appears in an old Hebrew writing with no obvious explanation.
Apparently, this figure is another calendar procedure because, when we add it to the 1st day of Tishri, it arrives at the Day of Pentecost, the 6th of Sivan, three and a half years later, and 50 days after Passover. So, the great festival dates were being used, in addition to their religious function, to hold together a surprisingly accurate luni-solar system.“Blessed is he who waits and arrives at the 1335 days.” (Daniel 12:12)
In summary, the pre-Metonic Hebrew calendar was a 7-year cycle of alternating 86/87 months, crosschecked by a regular 1335-day formula, and cross-checked again by a long cycle of 600 months after 481/2 years. Its distinguishing mark was a Sabbatical ‘stamp’ making it unique from every other national calendar.
Ive updated my paper and added diagrams and tables here: