Hi there!
It is possible to refund. But first let's try to fix that problem, if we didn't manage, we can refund it for sure.
1 - Make sure you are using EliMZ_Book.js somewhere above all Eli plugins. It is my core plugin.
2 - I think the problem could be that you are using an outdated version of the RPG Maker MZ. To make sure, you can update the core files inside your project by doing this:
Make sure to click on OK with the second line pointing out to 1.9.0.
3 - If none of that works, when the error happens, press F12, a browser window will open. Then search for the CONSOLE tab. Click on it and send me a screenshot of what is in there. This will help me figure things out.