Definition of Saeculum
The web page does not have an explicit definition of Saeculum. It appears to be two nine-year periods each with the 3 extra months. I reckoned the number of days in each such period to 9*73*30+31+27+31 = 19809 days, which lasts around 54 years. so seems to form half a Saeculum, which is stated as 108 years. I also calculated 3 Saros periods to last about 19756 days.