If GRZ and KRY (concession and contract) are so different

This is a common misconception IMO.

In fact KRY is contracted to mine a concession, where the concession holder is the CVG. Now the CVG is certainly a government controlled enterprise, but it is still the concession holder and the rules concerning that concession are exactly the same as the rules that govern GRZ's concession.

KRY isn't the concession holder but if all concessions were nullified than the CVG would automatically lose Las Cristinas just as GRZ would lose Brisas.

Now in a legal sense, the grounds available to KRY for recompense in the event of either the CVG failing to honour the contract or the CVG losing the concession to Las Cristinas are different to those available the GRZ directly being denied their concession, in the political aspects I doubt that Hugo bothers to acknowledge or recognise that there is any difference.