To the final question, no it isn't. Unless something has changed, you may be lucky to score a bargain.
The $US pricing requires an `18% gratuity to be charged at the restaurant, while the $AU pricing is inclusive. That accounts for much of the discrepancy, although I seem to recall Bayou/Crown Grill could be over $AU60 following a recent price rise.
Yes, that is the US pricing as the ship currently operates in $US, but AU itineraries are ordering in $AU. The app isn't clever enough to have dual currency pricing. From the same experience as Coral & Majestic prior to arrival, if you order them now you will pay $39 or $35 Australian. Only when the ship arrives will the app start to display the correct $AU pricing. The same also applies to Diamond Princess next season. It is possible Princess will find a way to square their ledgers, but not the last time I checked. I can currently order Grill on Diamond Princess for $AU39pp
The same happened prior to Grand & Majestic arriving in late 2022
Specialty Dining Cost Princess Australia - Australia & New Zealand Cruisers - Cruise Critic Community