Well, the Patriarch, on behalf of the Russian Church, did repent publicly for the sin of regicide (in which he and the Church really took no part), and has "officially" rejected Sergianism. I'm sure you've seen Fr. Roman Lukianov's article "The Path of the Russian Orthodox Church". http://www.pravoslavie.ru/enarticles/031216212711
Ecumenism and Sergianism have been rejected as official positions of the Russian Church- likewise, the New and Royal Martyrs have been glorified- a glorification with a number of obvious implications.
I suppose it boils down to whether one believes the repentance to be sincere along with the question of whether the sinfulness of individual hierarchs should (or CAN, according to Church teaching) be a barrier to eucharistic communion. I suppose it's here that the Donatist question comes in.
My 2 cents.