As far as I know, Cephalo never provided the source.  I even sent him a PM some months back asking him about it but I got no reply.  If anyone knows how to contact him ask him about releasing the source.  I'd love to take up the project and have the skills to do it.

Elementerra works fine.  All of those things mentioned above, except rivers, are randomly added to the map when you start a game.  I generally only use  Elementerra maps though I do tweek them a bit before I play them.

Or perhaps the maps I am creating are too large

let's hope he creates Elementerra 3 soon

Like I said, the resources are added randomly when the game is started.  Likewise so are Champions, Shards and Wildlands.  FYI: if you prefer to locate the Wildlands yourself, you can add them to an Elementerra map by using the Stamps then set "Wildlands" to None at game setup.

As I recall, Cephlon was frustrated that adding the resources randomly at start could not be turned off so he was stuck not adding them at all within Elementerra.  Though you can add some yourself in the Cartagrapher's Table.  Just keep in mind that more will be added at game start.  Perhaps you can add some manually in Cartographer's Table and set resources to "Sparse".

Yes, I know that Aerion, my problem was not that resources were being placed automatically, which I knew, but that the world is created with all barren land so there was no grain, materials or essence. So what you have to do is go into the map creator, load up the map and add in fallen or fertile environments so that grain and such will appear.