Yes, unluckily currently everyone (who's using the m2e plugin) runs into the same issue :-(
This is due to the m2e Eclipse plugins configuration of the projects source folders.
The plugin disables copying Maven resources (e.g. from "main/java/resources/*") to "target/" (via an exclusion pattern in the resource-related source folders). Therefore the imported model file isn't copied to "target/" and isn't available on the projects classpath (and "invisible" for Sculptors EMF-based meta model). This issue is tracked
in #25.
Maybe we have to come up with our own full-blown Xtext scope implementation which adds Mavens resource folders to EMFs internal resource repository.
Still investigating...
/Torsten