Figured it out. You have to launch the cei-launcher.p8 first, then once it makes the game files, you use cei-game.p8 to run the game.
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Sorry for the late reply, was overseas for a little while! I am not sure if your miyoo setup is different, on my pico 8 raspberry pi setup here's how i launch the game:
1. Move the carts into the pico 8 carts folder.
2. launch the cei-launcher.p8 via splore it should automatically generate data (world data and game data) and then launch the game cart.
As you figured out, in case it bugs and doesn't automatically launch cei-game.p8 you can just run it yourself :).