I think you want smoother cordage. I’d try fishing line, which is light, strong, and quite smooth. It’s also easy to find.
I second that recommendation. Some cheap monofilament fishing line would be the right tool for the job. Just make sure you use a proper fishing-type knot for monofilament or that could be the weak link in the system.
Your weight is way too light. If you have a clean shot / no lower branches in your way I’d take something like a small fist-sized rock & tape/wrap your leader line to that & then throw it over the branch. The weight will insure it comes back down. The way I see it you had a 1oz weight on the down side but multiple ounces of string on the ‘up’ side.
Decent bet that was cooking twine for trussing up turkeys & such.
But yeah, to echo @Spiderman you’re doing this about as wrong as possible. Good luck as you home in on the correct mix of very heavy weight, light string, and massive overkill on the launch force. That’s the combo that wins.