Yeah this works very well, but there are two problem with this approach:
1) Its unintuitive - only seasoned Fibery users know that multi-select fields are secretly hidden mini-databases.
Maybe having a normally off checkbox on the single/multi-select field creation modal for something like “Make these options available globally (in other databases)” which automatically does what you suggest, but creates them as “hidden” space/databases. Something like this:
2) It creates a bit of clutter - having to create several spaces/databases just to contain a few entities used as global single/multi-selects creates for messy relationships and clutters up the UI. Because then you have one or more space/databases which really don’t do anything more than hold a few entities.
Happy birthday by the way! 