If you love something you love it. I still have a teddy bear quilt on my bed and I am 68 years old. Add the frogs by all means.

I made a frog quilt for my 16 yo DD, and put a large print daisy fabric on the back so she could turn it over if she wants. She has always loved frogs as well, her room is full of them! Good Luck! :)

I just finished a quilt top where I fussy cut squares of just adorable animals for a granddaughter. I just used another color that would make the small forest babies pop and did a simple four patch. I just love it and it is such a precious and happy quilt. Your granddaughter is a lot older than mine but personally I don't think you could go wrong in any way you decided to design it for her. She would love it and it certainly would become a treasure for her.