Northbeach
The statement that after the A/T power reduction, caused by the radalt altitude change, the ensuing audible message was apparently not perceived as a problem (the crew were about to extend the gear at that point in the approach anyway) suggests that, the previous radalt faults may not have been perceived as a fault or indeed that the faulty radalt then immediately or after a short period started working normally. As such maybe no write-ups were made as it was not perceived as a problem?
No doubt the FDR data will be further analysed to determine what happened during the previous radalt events. But it's possible that this was the first time that the radalt remained in the fault condition.