When receiving event booking data via API, the default business location id (Main location id) is always specified. The location type is specified as CUSTOMER_LOCATION. And everything is also displayed correctly in the appointment calendar.
Application ID: sq0idp-FxCirmJPgV5wZogcT_TLNg
Reproduced on API version 2022-10-19 or newer.
If it’s displaying correctly in the calendar then whats the problem? The location is required but if CUSTOMER_LOCATION is specified the address is pulled from the address of the customer profile. 
The problem is that when we get data through the Bookings API, we get the wrong location ID. Instead of customer location, we get the business location ID for any event record received via API.
Right the booking itself won’t have the customers location in the booking response. It will contain the location_id of the business. You’ll have to call the Customers API RetrieveCustomer with the customer_id from the booking to get the address.