"The superlatives in the encyclical refer to the superabundant merits of Christ and should not be a source of any controversy."
Actually, that concept (superabundant merits of Christ) might be a source of great controversy, Alex. For example, how does God have a "superabundance" of His own uncreated energies? :)
Superabundant refers to that verse in St. Paul, "where sin abounds, grace abounds more".
I agree that the "Treasure of Merits" is a foreign concept to Orthodoxy, but it is a separate controversy from the Immaculate Conception.