Really great art style and concept! The bird and its clucking is really cute! The balloon physics can be a bit finicky, but mostly work! The last obstacle in hard mode feels a little random whether you'll make it past all the bees.
Just one suggestion (apologies if you're already tried this, or if it's not helpful) but it's possible if you connect points together using spring/hinge joints and draw lines between them, rather using physical line segments with a hinge joint on either end, the balloon string might be slightly more predictable. I went through many iterations of string physics for my game, and that was what worked for me.
The level design is really neat! I like that you have the sort of zip-line mechanics, where you hang by your balloons, as well as the fan-launcher mechanics. Also, love the music in hard mode!