What I meant by that was "being able to trade territory based on hexes in a region. Meaning that what is traded are not some selected separate hexes, but a whole region. By a region I mean a "battlezone".
Even if a country only controls 1/10 of a battlezone, for example Germany at the beginning controls only a few hexes of the "Lodz" battlezone (the majority belongs to Poland) the player could select that they want to give that battlezone region away to Poland. Or some other country (however that would make no sense, hmm - but could work in multiplayer!). What mean is, this could be a TECHNICAL solution of how transfering territories could work in a limited sense. People could just transfer ALL hexes of a single battlezone of their choice to a country of their choice.
I am suggesting this only in case this is much easier to develop (Balthagor mentioned that the difficulty is creating an interface where you could select separate hexes, so I am suggesting this on an assumption that trading whole battlezones could be easier). Again, an example is Victoria II game where even if you can conquer only whole regions, not single provinces.
I don't think this would create a problem of the map looking artificial, because there would be many cases where territories would NOT be traded, and for example after WW2 it would make sense for the UK and USA to trade ALL their conquered battlezones back to the continental European nations.
Sorry if my English skills prevent me from making sense :>
But a simulation game has the goal to teach you how to solve optimization problems.
By knowing the code of how Supreme Ruler economy works, you will learn nothing. You will however learn by experimenting with it and attempting realistic solutions to it. I am sure the Supreme Ruler economical code has no miracle solutions to the real life economy
But playing with it, without knowing all the technical details CAN be a way to learn.