Think we can predict the reply.
As Oz folk say..."no worries mate" .....will be the answer.
You stated this ....
"(and yes, we can't know - that goes without saying)"
Your example of changing cost of option up to 800k is a good one.
Not a good comparison but when they introduced the insurance requirement for non O-A extensions they made it retrospective, so I don't trust much in this lovely country.