Well, there is a little problem: any doctrinal statement in the Acta of a council the Latin church calls an "Ecumenical Council" is actually a dogma of the Latin church, whatever those who want to limit the teachings of the Latin church to the content of the recently issued "Catechism of the Catholic Church" may want to claim.
Purgatory is a dogma of the Latin church, as it was defined by the purported Union Council of Florence/Ferrar, which the Latin church claims as ecumenical.
Of course, from an Orthodox point of view, rejecting the dogma of purgatory is not a modernism, but a step back toward the Faith Once Delivered to the Saints.
The root of the Orthodox objection to the Latin dogma of purgatory is that it is part and parcel of the ideas of Barlaam the Calabrian that grace is created, rather than being a manifestation of the Uncreated Energies of God. Indeed, if you ask one of our most traditional monastics what the biggest hurdle to reunion is, he (or she) will probably cite 'created grace' (not a phrase the Latin church uses, but a short-hand for the Orthodox critique of Latin soteriology, purgatory included) not the filioque (which John Paul II seemed, correctly, willing to yield).
The filoque has been adequately explored on this thread.
The IC of the BVM is also a serious problem, since it, together with the failure of the Pope to insist upon the bodily death of the BVM before her bodily assumption (which has always been taught by the Orthodox, but *after* her death), leave as a permissible position within the Latin church, if not an actual dogmatic teaching, the plainly heretical position that the BVM has a pre-lapsarian Adamic nature, not a human nature as we now share. "Not assumed, not redeemed" was the cry of the Fathers against the monophysites, monothelites and monergians.
From the Orthodox view, the IC of the BVM comes very close to vitiating the basis of our salvation. (And, since the condemnation of Pope Honorius was dropped from the papal coronation oath, makes us wonder whether the West isn't still soft on the heresies which denied the full assumption of our humanity by the Eternal Word, but stopped short of monophysitism.)
Thanks