Yes, you should see all nodes that are in API mode output an Aggregate Addressing Update API packet if they receive an Aggregate route update.
As an example, I setup 3 radios. 2 were in AT mode, the other in API. All radios were set to default with the AT/API mode being the exception.
I sent an ATAGFFFF from one of the AT radios. The API radio output an Aggregate Addressing Update API packet while the AT radio did not output anything.
Both radios, however, did change their DH/DL to the address of the sending radio.