No, you can only return the cards that were exiled by that specific instance of a Synod Sanctum.
When a card refers to itself by name, it refers to that specific object only.
201.4. Text that refers to the object it’s on by name means just that particular object and not any other objects with that name, regardless
of any name changes caused by game effects.
If the object leaves the zone that it is in, it loses all memory of what it was before it moved. So even if you can bring the right Synod Sanctum back it won't have access to the cards its previous instance exiled.
400.7. An object that moves from one zone to another becomes a new object with no memory of, or relation to, its previous existence.
There are nine exceptions to this rule: (but none of them make this