The contract doesn't really address any % split, rather it defines the royalty rate and exploitation tax.

If we end up there, the attorneys and accountants will do a detailed analysis of costs of production, to come up with a basis for the amount demanded and I would expect them to make it the largest number with any logical support calculations.

As a matter of strategy, it's great to get the other side to engage in an argument over YOUR numbers and calculations. By contrast, they would try to avoid our calculations and first deny any damages, then as a back up position argue a very low number, like amounts actually invested.

Assuming you win an award, arbitrators tend to award some amount in between the two that has a reasoned basis that the arbs think is fair.