I've heard that in FBW Airbuses, if your sink rate on finals is low for
whatever reason, the computers might not consider it to be a landing at
all, and might actually prevent reverser deployment and even inhibit
brake application on the landing roll?


You may be referring to the accident in Warsaw some years back. It was
the gear switches that didn't report landing, IIRC. It makes absolutely
no sense to connect landing detection to sink rate on final.

As for the incident in Russia yesterday, the A310 is not FBW.

--
Thomas Borchert (EDDH)