Three things need to happen...
The regulatory side needs to be stripped from CASA.. Make them work as enforcers of the law.
Enforcement needs to progress through the CDDP as a normal criminal matter.
The Power of the AAT to ignore the normal justice procedures (in all matters, not just aviation) needs to be curtailed.
IIRC the AAT was set up as a stepping stone to try to alleviate use of the courts time and resources, to try to get matters solved before. These days it appears they have grown the ability to over-ride the courts and make their own way through the muddle.
A law stating that it is a defence to declare to the AAT that you regard the charge as criminal matter, and that you wish it heard as such and force it back into the criminal system should be enacted.
In the criminal system, some charges are not normally handled by some courts, although that court might be your first appearance. I.e a charge normally handled by the county court will be initially heard at a magistrates court. The courts limited jurisdiction is announced to you as the defended and you are offered a denial so you can goto the higher court. People pleading guilty will invariably accept the terms, leaving the county court open for the appeal.
In the AAT your next place of help is the High court, you've already spent 'thousands' 'defending' yourself.
Sorry but the AAT is nothing more than death by bankruptcy, and sooner its 'powers' are curtailed the better