The point is that, nothing will really happen if you just fly visually and land, but I do think, the FMGS should agree with the actual landing runway.
I wonder what would an insurance company would have to say if you happen to skid off the runway, and the FMGS has another runway in the database? Have you thought about that?
I know this topic is not that relevant, but as an Airbus pilot, and as the manufacturer is trying for us to "operate", every single procedure must be done as listed in the FCOM/FCTM etc.
The FCOM4 states that on visual approaches the landing runway should be inserted on the active flight plan, so what to do?