Assume there are bugs. I'm sure there are bugs. While I use Game Modules 4 in my own project, Legend of the Stones, there is a good chance I will not encounter all of the bugs that exist.
Please always back up your project, and before installing Game Modules 4 or any updates, make sure you only import the content you want to import.
That is to say, if you do not want the Demo content, then do NOT import it.
Demo projects are intended to be standalone projects and should NOT be installed into your main project. Instead, install Game Modules 4 from the Pacakge Manager, and then install the demo game project.
It is also best to use the Editor version that the demo game uses, which should be specified on the Asset Store description.
They should work in future versions, but for the purposes of learning and experiencing the demo, best to stick with the version they were created in.