CoreData + CloudKit: Transient Properties Across Configurations

I've defined 'public' and 'private' configurations in CoreData and configured the 'public' configuration to be handled in the CloudKit publicDB. The two configurations contain disjoint sets of NSManagedObject entity types. Some of the entities in the private configuration reference an entity in the public configuration using a UUID; thereby avoiding cross-configuration CoreData relationships. Avoiding this is a requirement of CoreData + CloudKit.

Now, since the UUID is meant to point to an object, in the awakeFromFetch() method I decided to fill in a transient property. No go. Even for a transient property there cannot be a cross-configuration relationship.

Why? Is there a way to avoid this constraint?

The cost of not having a transient property is to do a fetch of the object based on the UUID every time it is needed. Is this something that one should never worry about?