Welcome to cruise-chat.
The last time I was aboard a ship with the specialty restaurants was last year and the age was 13 and above at all times. I'd say they have modified that to allow for early family dinners (the before 7pm thing) since then, otherwise the website wouldn't say it. But then the RCI website is not especially impressive to me and is filled with errors and glitches. It was never 12 years old, so the second person you talked to was wrong. Welcome to another fun thing - getting different answers each time you call them.
I think the first person's info is correct. Make the booking for two on-line and then go to the specialty restaurant as soon as you board the ship and have them adjust the reservation.