As per your posts, my genealogy files are stored in both Devonthink and Mac Family Tree
Yes, the files are duplicated - not ideal, but not a problem
In fact, the duplication/redundancy serves as backup
My data is backed up (both Devonthink and MFT)
locally using TimeMachine
and “in the cloud” using Arq Premium
No need for the setup complications of iCloud and indexing folders