Not sure about the bus/FMGC but would be interested to know how easy or difficult it is to check which database is installed and active on a 'bus". Certainly according to our FCOM the database check (preflight, Boeing) is simply:
"Verify that the navigation data base ACTIVE date range is current.".
That is it, no check of database ident....then again perhaps there's no danger of getting the wrong "sort" of database on a "worldwide type".