The selection of reverse (especially if only to reverse idle) is desirable for symmetry of blocker door drag.
The manoevres carried out in this case are nice and quick after the surge, so IMHO the engines don't stabilise at low (or flight) idle prior to reverse and so there is unlikely to be significant change in engine power. The effect of engine usage and risk of inducing physical damage is moot.
The ECAM will identify the faulty engine, if the FADEC had applied its detection, reporting and recovery processes.
The aircraft tyre smoke indicates quite heavy wheel breaking, whilst reversers are deployed for only a few seconds. This is suggestive of low reverse power, possibly not above reverse idle on both; this itself could be supporting of the speculative view that the crew were not even trying to be certain of the faulty and normal engines up to and during the reverse selected period.
These comments and speculations are my own view; I do not wish to imply anything other than admiration for the handling of the event and adherence to SOP.
(Basil and lomapaseo, I started writing this offline, I wouldn't disagree ... as its not R&N I decided to paste anyway)