I'm an Australian citizen too.
The Constitution is interpreted under Constitutional law, as stated by the High Court. It can only be applied in the context of that legal meaning, which is not the same as a reading by an interested but untrained citizen.
> we are still governed by the Queen in practice...
I feel as though you may be misquoting your famous family connection.
In a constitutional crisis, do you sincerely think the High Court would say "oops, I guess we're the personal colony of a Queen who suddenly upended hundreds of years of Parliamentary Supremacy somehow"?
If you know a bookie who'll lay odds, I'll happily take this wager.