Hi, If you log in to the Celebrity web site you will see on the menu 'Manage my booking'.
You can then see all the restaurants and also the prices for the speciality ones too. You can make reservations (except for Blu) on the site now if you wish. There's no charge for the MDR's i.e. Tuscan, Cosmo, Cyprus and Normandy. You say you're Aqua class so you can use the Blu restaurant at no extra charge; I think you book this one with your Concierge. Luminae is exclusive to suite / retreat cruisers.
If you've got 'on board credit' you can use it towards the speciality restaurants when you've reserved them at the 'Checkout' page. Same goes for excursions, and other packages.
I gather Eden is very popular so I'd book now if you want to go there.
Worth a look at this before you pay any extra; Celebrity Beyond Food Review - Which Dining to Avoid & Must Try! - Bing video
We're on Beyond in a couple of weeks 🥳.
Kind Regards - Susan and Michael