I see an Emergency AD coming out as a result of this. From all the posts looks like the aircraft did as designed. Well of course except for it happening in the wrong flight phase!
I appreciate also the reason behind the thrust rev amber indication needs to be fully investigated but the config change to the aircraft is the more pressing issue.
I would imagine a interim measure which would call for the deactivation of the auto flap function for the LEDs then in future a modification that would incorporate throttle lever position into the logic that the FCUs use for the auto flap function. But both of these would take some time to produce the necessary Service Bulletins.
As an engineer I could see a short term fix to prevent the change in config that this aircraft suffered from and that would be to arm the alternate flaps during the take off roll. Then once in the air deselect and operate the flaps normally.