Hi Mathias,
So far, it is not possible to specify conditions for 'id:reference[]' classification. You can only explicitly specify object types that should be available in the selection list and thereby indirectly exclude all other object types. We are thinking about a more elegant solution.
However, I do not really understand what is the behavior you would like to implement for your selection list. If you want a selection list of object types, the schema is evaluated that does not contain metadata of individual objects. The schema can only tell you which property is referenced in which object type and only knows about its general attributes. A search for concrete objects with specific metadata is a different topic.
Best regards,
Antje