Eh, my post was kinda unclear.
Depending on how old Moon was-- could be 14, could be anywhere above that (I'm thinking 19+)-- her time in the war was 14 years ago minimum, possibly over 20.
If Mina was the same age she'd be somewhere in her 40s too. If she was older, 50s maybe? Voice actress is also in her 50s but that's not a reliable way of guessing a character's age.
She aged much better than Moon physically though. Or at least looks eternally 14, just with some eye bags.