I have been thinking about taking some classes as well, but with kids and a full time job there isn’t much time left in the day. Could definitely use something more focused in Blender/GIMP/etc, as you can see below from my failure to create UVs after following multiple tutorials… 
So I remembered as I was writing this that you can put arrays in structs and then those structs into arrays. So I updated my system to use that instead. Can’t tell the difference performance-wise, but probably the better way to do things.
Here I have implemented a basic Marsh generator:
Any given lake only has one river exiting it, but can have multiple entering it. If a river exits a lake and re-enters it, then I generate Marsh around the lake and the river that is looping back into it.
I think I will create a lowland generator so that if a river passes near a lowland, the lowland is next to a lake/ocean, or the lowland tile is Wet, then it would naturally form a Marsh. Lowlands will only apply to plains tiles. Then I can tie lowland generation to a map setting so players can play with the global marsh coverage as they like. Also, I may work out some Marsh Forests.