For reference, please point your developers to the Database API documentation on the developer portal. If your development team decides to not leverage the Database API but rather access the raw underlying tables, ensure they take due diligence to ensure only READ operations are performed, no schema changes are introduced, and extreme care is taken to ensure query locks are not excessive (ideally if at all possible use the WITH (NOLOCK) hint on the queries).
While the database schema has changed little over the years, only the Database API is supported by BigFix. Accessing the database tables directly may cause issues in the future should the schema change. As such, they should check the database schema version to ensure integration compatibility. They can pull the current database schema version using a query such as:
SELECT TOP (1) [Version] FROM [BFEnterprise].[dbo].[DBINFO] WHERE [ServerID] = 0