Clumsy, Glasses and Spicy: 10. Sheep: 13 at best. Hungry: maybe 14 or 15 (she definitely comes off as the oldest of non-adult nuns). Pancake: 55 probably (considering the convent was formed 50 years ago, she does not look 8 here.) Mother Superior: Somewhere in her 60's (she also does not look 20 in that image where Pancake is supposed to be 8).
As for the others, I did not have any guesses, but I (correctly) expected most adult nuns to be in their 20's and Star nun to be in her 30's.