If you set the maximum occurence of child object to unbounded, the child object needs to be on the many side of your association. It makes perfect sense to have a *-1 association from child to sample.
The other “problems” seem to be based on the regular naming conventions of mendix (capital letter at the beginning, association naming). Does this result in any problem? Usually, you use a mapping to import/export data from/to xml. That means, it does not really matter how all this is called in the mendix domain model.
The generated entities are meant of one example of a domain model that the XSD could map to. You can change it however you want.