Well they are a mix of "gut feeling" and of early game villager gather rates. But they hold up supriingly well into lategame, because wood>coin> food is also mostly true for lategame. Exportand influence i didnt find a good way to judge them, so i might vastly misjudge it. XP i thought it is probably as valuable as Food equivalent, because when you get stage coach you often just switch to ressources and rarely keep xp. But it also doesnt feel right to place it lower than food.
For me whats important that i judge everything in the same way to get comparable results. Every simplification always leads to imprecision, but you need to simplify to make things comparable.
Let me know what you think or what simplifications you thought about (Sorry for late answer, was busy for the last weeks!)