There was an error there on the EVL file is ContextModel (class inside ContextModeling EPackage) not ContextModeling, sorry. When I validate it nothing happens... And it should because the check is always false.
This appears to be a bug in the EVL-EMF integration, which assumes that all elements in a model are instances of EClasses that belong to the same EPackage. We'll try to fix this  but, as mentioned in a previous message, you're likely to find out that there are other cases where EMF-based tools don't play well with sub-packages so my recommendation would be to consider flattening your metamodel.
Sure - feel free to add yourself to the CC list of the bug to receive updates. If this is a blocker for your work, I would recommend considering the proposed workaround as it's unlikely that we'll be able to look at this within the next few weeks, due to other commitments.