Music was one of the last bits I wanted to get in but I was running out of time. I regret not focusing on it sooner because the lack of any sounds at all really stood out to me.
I’ve added a not to the page description about removing nodes/edges since you’re the second person to bring that up. Something I should have made much easier (but you know, I used all the tools a bunch so they were familiar and I forgot what might not be obvious). You simply hit “Backspace” on your keyboard (or “Delete” if you’re on a macOS keyboard) after selecting a node or edge.