For fixes and errata... just wait for the next block to be writen ! and reprint the car with the fix !
for compensation :
if volition use is own "token" to buy and sell cards & booster.
if a ban occur -> refund in token value
errata/nerf -> refund in token value of the différence of value ( for exemple : between the anoncement of the nerf and.... one weeke later?).
or... nothing at all ! like in other CCG !
I prefer the "nothing" solution
and maybe ... the creation of a "legacy" tournament rule !