The thing is that Rapunzel ISNT a comic relief character in the second act. In fact she is one of the more tragic ones.
She was a shut-in that goes slowly insane.
I never got this until I read the amazing storybook of Into the Woods that is out there, but she actually commits suicide by throwing herself beneath the giant instead of having her heart torn in two by her love for the prince and her mother.
She is only really funny in the second act when she cries at the end of Agony 2.
Frankly, I have always felt that her descent into madness is one of the more poignant themes in the show. It is a small part, but so much can be done with her.
Baritone in search of a role in a new musical...