Except that treaties are unilateral, and hence not an actual contract, you cannot hold the other party to the contract because they will simply say that you weren't a party to a unilateral good faith agreement they made with some land stalwarts centuries ago. If I make a promise to a city and then I don't deliver on that promise nobody from the city can claim to be a victim even if their life and livelihood was entwined in me delivering on that promise because people are allowed to make all kinds of Grand Gestures and not deliver on them. If you gave me money/consideration for my promise then of course you should expect me to deliver on that promise.

In the terms of a good faith agreement, the very first instance where it was neglected or overstepped renders it invalid/null, in other words the single party that made the promise failed to live up to their magnanimous words.