Hmmm… I don’t see any immediate problems. A few things:
The builtins are read-only. In Editor 2 you can do temporary changes to those files, build and see the results. However, your changes will not be saved to disk.
Does this mean that you see the object but it’s not textured? What happens if you set the frag color to a constant:
// red
gl_FragColor =vec4(1.0, 0.0, 0.0, 1.0);
File locations have no impact at all. The references from the material file to shader programs needs to be set correctly, but once they are set you can move files and the references will update automatically.