Thanks for playing. We are sorry that you had a problem with the cursor, and we are looking into how to fix it. Unfortunately, we don’t have a Windows machine at our disposal, only a virtual one. The mostly tested versions are for Web and Mac.
In the spell puzzle, you need to grab (by left-clicking) spells from your inventory at the bottom and then right-click on a scene to cast them. You are absolutely right: we need a better explanation of the process.