Dear John Mark,
Your question is an interesting one, and is one that Peter Farrington and myself have raised with the Eastern Orthodox; of course some of the latter do not (alas) regard us as Orthodox at all, and so at times one can end up with the oddest sort of discussion. The strangest one was when some EO tried to insist that St. Isaac the Syrian has not been a member of a Church they called 'Nestorian'; this was very odd, since it was the EO who called the Church of the East Nestorian in the first place.
That bears on your question, because it is clear that all Orthodox and Catholic Churches regard Issac as a saint. One of the bones of contention in the talks about unity is what we do about the issue of saints, because there are those in the EO who refuse utterly to regard Sts. Dioscorus and Severus of Antioch as saints. Mind you, the Russian Patriarchate does not, if memory serves me correctly, accept ROCOR's definition of Nicholas II as a saint.
The process by which saints are made in the Orthodox Church is far less legalistic than in the Roman Catholic Church - and it would be useful to have more information on this subject. My understanding (which is probably as fallible as my memory) is that we do recognise the EO saints, even if they do not recognise ours.
In this is love, not that we loved God, but that He loved us and sent His Son to be the propitiation for our sins. (1 John 4:10)