A flag is not a photograph
The way symbols are defined determines which details matter.
The Southern Cross shown on the flag makes its own rules about which details should be realistic.
A flag is visible from both sides
The flag itself makes it a rule that the right-hand star is higher and smaller than the left.
That rule defines the flag’s reverse, as viewed from the other side, as incorrect.
With so much creative license in the design already it makes no sense to retain the one trivial nod to realism that makes one side completely wrong, while being undetectable on a moving flag.
The asymmetrical design has no special significance
Whatever reason the designer had for being astronomically precise at the time carries no value now. And putting a different design on the reverse would be a terrible idea for many reasons.