Auto-assign property based on data sources or transaction description

I have a duplex, and the Property under Transactions is not auto-assigned even though the unit number is right in the Description.

Why can’t we set this up under the Data Sources? I’ve asked about this since Stessa first came out. Why can I not assign the Property that the Data Source should be directed?

There is no way I’m manually going through all of my transactions to assign these.