1. Question: Why are FUs are not created / updated directly when creating an order / delivery ?

Answer: In case of the creation of new addresses / one-time-locations / locations or if FUs are locked in TM the TM specific processing is scheduled in a BGRFC queue and processed later. The queue can be monitored via the standard BGRFC transactions like for instance SBGRFCMON (bgRFC Monitor). The name of the queue (Inbound destination) relevant for TM is TM_BGRFC_INBOUND. 

For more details concerning TM and BGRFC refer to the note 2526415 (Updated trigger concept using bgRFC processing). Remark: Initially you have to execute the report /SCMTMS/TRIGGER_SETUP_BGRFC once in order to create the inbound destination.