A property on Fabrica is held by a Fabrica Trust. The original deed that granted the property to the Trust is recorded at the local county recorder. You can find a copy of the deed on the property page, and verify the same deed at the local county.
After that, every time a property gets transferred on the Fabrica system, the transaction gets recorded on a public ledger online that you can easily browse. Open the property page and click on the Transaction tab to see all the transactions of the property over the Fabrica system.