How can I reference data across documents and workspaces?

I have 4 workspaces, as I divide between my clients.
In my master workspace, I use common data (eg Country list).
How can I use that data as Reference in a document in a different workspace?

Currently I maintain the same table copied in different workspaces/documents, but would be good to have a single source of truth to avoid mistakes.

You can’t reference across documents. What you really need is to combine your documents into one and use Access Rules to hide sensitive data from the appropriate clients.

Understand this would be the way to go, but the business risk of exposing data from one client to another because of a misconfigured access rule is too great. In that case, I prefer continuing with my approach, where the risk is more limited (eg data not consistent across reference tables).
I’ll think about it… perhaps I can just run a script regularly to ensure data is the same in my reference tables in each workspace (perhaps the sync_tables method could be useful, haven’t played with it yet)