The answer is that the Din associated to the left is the strenghtening of the Tum'ah of the left. The demise of the latter turns the Tikkun of Gevura into Chesed for Yisrael.
Accordingly, we saw that at ז"ך of the left is the beginning of the covert Hanhaga of Atik Yamim. The above, then, explains how the counts of the left and right add up to form the count of Atik Yamim.
Sepher Daniel 7:22 seems to be in agreement:
עד די אתה עתיק יומיא ודינא יהב לקדישי עליונין וזמנא מטה ומלכותא החסנו קדישין
קח
