There is no fixed or computable phase relationship in optical wavelengths. But the constellation could operate as an Earth-sized radio telescope pointing all directions at once, probably for a few seconds a day to avoid exceeding downlink bandwidth. There, the phase relationship is anyway computable, in principle.
Probably they have not, yet, because they will be lofting new ones all the time, so have time to get it right. And, it might not really be computable, in practice.
Probably they have not, yet, because they will be lofting new ones all the time, so have time to get it right. And, it might not really be computable, in practice.