Could the situation be similar to how it worked out in Chalcedonian Orthodoxy when one of our hierarchs (St. John of Shanghai and SF) reintroduced many of the western pre-schism Saints to us? I know that you're main focus is on the Saints before Chalcedon, but perhaps it could be a parallel situation? Just throwing that out there.
Ah, you're wondering why I am focusing on Hilary, and thinking it's because he's a pre-Chalcedonian schism figure? Yes, you're right. I've been putting some effort into studying pre-Chalcedonian Western Saints recently, particularly Hilary, Ambrose, Irenaeus, and John Cassian. I really wish that the OO were doing more to make Westerners welcome; at this point in comparison to your church the effort is truly abysmal.
I'm also pretty sure that all of us recognize St. Isaac the Syrian, but he was Nestorian, right?
No, I don't think it's appropriate to judge Isaac one way or the other. I'm aware that he has a great amount of recognition in both of our traditions. And I'm aware that I have and will receive a lot of flack for this opinion. But as far as I can see, it isn't universal and official in the OOC and I think it violates Patristic principal.
Anyway, I don't see how Isaac is really comparable to Hilary. Hilary was actually clearly orthodox and part of the Orthodox Church.