Thanks for the reply. I moved EliMZ_Book above ELI_MZMessageSounds and it now looks like the above.
The game now runs. I set up preset sound 1 and set it to the default message sound but nothing happens when I bring up a text message in-game. There are no errors showing. I think I must have set something up incorrectly. Here's an empty project with the setup: https://drive.google.com/file/d/1xiRUSuyJWLsdFUR6I8lms7zm8kYb0jGV/view?usp=shari...