The glyphs tell us more. Important to notice is how already in the 15th period the coming dark half of the year is defined:

15
	Ga4-23	Ga4-24	Ga4-25	Ga4-26	Ga4-27

6 + 6 = 12 half-months (representing the dark two quarters) are visualized by wedge-marks inside the perimeters of the ovals in Ga4-23--24.

In E the half-months are defined as 360 / 24 = 15 days. In period 15 of G we therefore, presumably, should read (6 + 6) * 15 = 180 days for the dark half of the year.