Thanks Barkingmad for sharing your experience. Makes sense that it might have been ice crytals encounter/icing? Encounters that we had here were located in SubSaharian Africa with TAT anomaly (confirmed by FDR) and all other ice crystal indications: light to moderate chops, in the vicinity of CB, NO weather radar return, "rain" sound...
Why Boeing doesn't address it with a NNC on B737NG is a mystery...
On the Airbus side, thanks to the document PantLoad provided, it seems like there has been some engine modification.