I would like to know like the "cover" what really is just the outer title image is there away to change the skin of each book I would like different books with different leather colours and so on.

Also you need to create a handle if the xml is invalid to just drop the book rather then letting it crash the game..

Been able to style the buttons and outer skin like the cover per book would be really useful.

Hello,
There's a way to specify a custom model for each book, but it only changes the item model. When you open it it still shows the same.
There's a way for to provide new background renderers, to show different books behind the text, but it requires a mod to provide the rendering code for it.
Currently I don't have any way to change the button styles. I can maybe look into adding some feature for it.

What mc and mod version are you on?

As for the crashing, it shouldn't happen, the book should display the error when you open it. Can you show me the crash log?