Hi, I want to like this - but I can't seem to get it to do anything.

Some honest feedback is the UX is not at all friendly, and after 5 minutes of trying I couldn't generate a curve from the example. I got to the point where I had to chose a date that has at least one data point. But how do I know what that date is?

IMO, loading the example should fill in absolutely everything needed to generate a curve. Including the points, definition, rates, and schedules, and then show something instantly.