Yes, the order of units in the second phase is completely deterministic. The order is based on the final location of your units in the first phase, except Alear, who's position cannot be altered. The order in the second phase is ordered from the top from left to right. Using this video as an example, position 1, 2, and 3 would be Mauvier, Kagetsu, and Lindon respectively. The units the furthest north in the first phase become the lowest in the order. If multiple units are in the same row, the further east the unit is, the lower they will be in the order.
