As the task description suggests, the product verification sheet's federated properties tab hasn't been used for the past few releases. Moreover, it's not clear what the scenarios that were being tested are. Instead, I reviewed our automated test suite, namely item.ts and prefatching.ts.
I set up a local Wikibase instance with federated properties by manually executing the tests. They seem to adequately cover the basic usage of this feature, including:

• Creating an item and adding federated properties to it.
• Ensuring that the item's data is retrievable in json format and not in unsupported formats like TTL and RDF.
• Validating that the addition and deletion of federated properties are reflected in the item's history page and Wikibase's recent changes.