Thanks for your detailed feedback, it's very helpful!
For the ungrappling, it is possible to ungrapple specifically one anchor by clicking on it again, the space bar detaches all anchors, I admit, it is tricky to pull off when swinging at high speed... I made some levels that would use it more but they were too janky to be in the final version.
For the difficulty, there are definitely some level that I would want to tweak in the future (eg. level 12) by adding space, make them a bit more forgiving and maybe add a trajectory line when you swing.
I haven't seen the bug during development and testing, if you can tell me how to reproduce it, I'd be happy looking into it.
I'll definitely keep you posted if I continue developing after the jam :-)