Unlocking other books (alternative) :-
1. Open the game and go to Book Purchase Menu.
2. Wait until all red lines disappears.
3. Now open the menu and use save data. (Read "Save/Restore Data usage below for details).
4. Now open the "MagiumSave.dat" with a text editor.
5. Search for line "first_book_purchased" and "second_book_purchased" (mostly line 41, 42).
6. Change their value to 0 to 1. And save the file.
I am trying my best brother. I am really busy with my college and rl. And as this games need to be modded from scratch every time it's time consuming to do that. But I am trying my best to utilize my time to mod this again.