While I agree with what you’re saying about the difference between nationalism and irredentism in TTL’s Greece, we also have to remember this is the third costly war in 30 years that the Greeks have won against Turkey. Combined it’s likely about a million Greeks have died in or because of these wars. I’d be surprised if there was a single person in the country who hasn’t lost a friend or family member to the Turks at this point between military losses and the deaths of civilians. And that’s only in living memory and ignoring any grudges for other reasons. The people of Greece will see weakening Turkey as much as possible as essential to the continues health and safety of Hellas. They won’t care that the land used to be there’s. They just don’t want Turkey to have it. So I don’t think they only want Constantinople, that’s just what’s most important to them.I think we should first take in account what TTL Greece wants. To a large extent TTL Greece is the product if Venizelos' ideas and he was more a nationalist than irredentist. See for example how he played with the Pontic issue. That means that Greece wants the land the Greeks live in and prosper.
Therefore, by this point Greece probably wants Cyprus and Constantinople to fullfil he national vision, plus whatever reinforces her borders and the prosperity of the nation: ie more defensible borders. Minor extra concessions which include natural resources could be added, perceived as reparations for the enemy attacks.
That said, Greece doesn't seem tonask for so much, appart from Constantinople, but this is also a matter of how the USSR plays. It might seem far better even for the USA that Greece keeps Constntinople, if this way the USSR is kept away. Furthermore, if the involvement of the US forces in the Greek Front means a closer cooperation of Greek and American policymakers and economic cooperation, it is no unlikely that the Greeks can appreciate the American policy of lessez faire: if the economy of Turkey and which ever Balkan countries stay within the western sphere are more to international commerce and capital movement, Greece can benefit. Otherwise, if the post-WWI model (economic spheres) prevails, the Turkish economy will be closed to the Greek businesses for a long time.
Therefore it is not unlikely that Greece aligns more with the USA and vice versa.
Honestly I think that unless it directly harms their personal goals (international Constantinople for example), the Greeks plan to support any and every claim someone might have on Turkish lands. French Armenian Cilicia? Why not, demographics are for squares. Soviet Pontus? Sounds good, you want some communist Greeks to put in charge?
To be clear I’m not saying that this is the best or smartest approach. But politicians backed by angry voters who want their pound of flesh don’t always make the right decisions. So I think they’ll try to grab as much of Turkey as they can and support others grabbing as much as they can, to minimize the Turkish threat as much as possible in the future.