I must say I am with Chenier in this, for the most part anyway. His system is very easy to grasp:
- Peasants hungry -> get them food
- Peasants unhappy -> get them goodies
- Need to build something cheaper -> get materials
A somewhat small step such as this would already improve the trader game a whole lot. With this the food shortage realms would have something to trade back, which would be materials, that they would anyway produce more than they need. Even if this were to be expanded later on, it would be a smaller step that could be taken before more variety is added later. Even without more complexity later on, it would still stand by itself very nicely.
The steps taken could be even smaller. You could start with introducing the goods and see how that works. Tweak it to perfection, let the traders and lords get used to the new resource, get more experience and feedback from the new kind of trade and use all that knowledge for the design and implementation of materials.
"The peasants of your region are happy for all the available goods."
and then perhaps later:
"The availability of materials helps to restore production."
"The abundance of materials boosts production to 107%."
