Is there a way to regret the last set node of the curve tool? When pressing ctrl-z it removes the whole curve. If pressing esc it removes the curve and switches to move (hand) tool
You can use right click at the end to choose if you want to keep or discard the last point. ("Finish polyline here" or "Finish polyline at previous point"). Once it is committed you can't add or remove points from the point list.