More exploration:
> When you add a library block to a subsystem file, the data dictionary attached to the library becomes available to the subsystem file. If you refer to the subsystem file from a model using a Subsystem Reference block, the library dictionary is available within the Subsystem Reference block boundary only.
This implies that I should be able to attach a data dictionary to a library, use library blocks within a subsystem, then insert that subsystem into a model. The model won't have access to the data dictionary but the subsystem should. However, this is not the behavior I'm seeing on R2022b. Trying to build the model containing the subsystem reference results in an error; it can't find the reference to data dictionary information even though the library references are contained within a subsystem that should see the data dictionary.
Attached is a sample DD, library, subsystem, and two models (one with the library reference directly and one wrapped in a subsystem reference) that show this difference in behavior.