This system is very experimental, we are still seeing if this makes sense to use and if this is the best alternative. Please report issues.
If the database is renamed, the old generated class is not deleted.
The new way of referencing DatabaseAssets via WorldObjectReferences only works for GameObjects (by design). Ideally this should be separated by type or category, and have a way to not depend on guids, I was thinking on testing some stuff with the localization table for ids.