I will try to be brief, I don’t wish to get entangled in minutiae.
Orthodoxy refers to correct belief and worship.
Orthodox Christians are not permitted to share communion with non-Orthodox. If it so happens that an Orthodox Christian…even a priest or bishop…should knowingly share communion with a person or church which teaches error that person could also be excommunicated. This is the discipline of the church altogether for nearly two thousand years. It is the knotting in the netting, so to speak (and has worked pretty well).
So if “Orthodox in Communion with Rome” did mean something, anything at all, it would mean that the church in the city of Roma was Orthodox. Which of course, it is not.
The best 12 second description of what the term would ideally represent was this declaration from Archbishop Elias Zoghby (May his Memory be Eternal!) the Melkite Archbishop of Baalbek, Lebanon. To many Eastern Catholics (like myself at one time) this man was a genuine hero.
What he is saying here is that his relationship to Rome is conditional. This is not the position of any Latin bishops that I am aware of. He is not necessarily accepting any changes to the relationship introduced in the last ten centuries.
The objective here was to establish a base from which the Melkite Archbishop could be in communion with Roma, and also Holy Orthodoxy. This declaration was submitted to the Holy Synod of the Melkite Catholic church, which overwhelmingly endorsed it. (The only two bishops who voted against this proposal were bishops in the diaspora who were appointed by the Pope of Rome, not the Patriarch of Antioch). The Melkite Patriarch went so far as to offer to resign in favor of his Orthodox counterpart if a reunion between the two Antiochian churches could be achieved!
Realistically, no Orthodox can be in communion with Rome as long as it teaches some of the errors which are attributed to it. Now this person or church may not actually believe those errors themselves, but the fact that they continue in communion with anyone teaching errors means that in effect they are saying it’s ok, or even more strongly it could seem as though they are endorsing false teaching.
So the idea that one can be in communion conditionally is a form of wishful thinking. A type of pretense.
Michael