Hello skeletalsabaki,
I have been trying to make terragen scenes based on art movements as well. For me, I have been pursuing the American Luminist ideal which suits my believes and eye just fine.
First off, It sounds like your very very new to terragen. So you will have to except that making a terragen scene that fits into the movement your pursuing, without being able to first make a basic landscape is going to be impossible. What I mean is that the art works you showed and movement I mentioned have very specific rules and ways of thinking. So for example, if we can not yet build a cloud system that looks like a photograph, then we will never be able to build one that looks like a Luminist sky. clouds are hard enough, making them look like the gate keepers of paradise is real work.
Don't be dissuaded, what you want can be done! But first you will have to grind your teeth. Start with the following tutorials and forum discussions if you have not already done so.
http://forums.planetside.co.uk/index.php?topic=12630.0 http://forums.planetside.co.uk/index.php?topic=7733.0by doing these tutorials repeating them and then altering the process you will get very close to what your tying to accomplish. Then post the results in image sharing and the expert terragen users will help you get the rest of the way. It's going to take a lot of time and persistence.
If you are not a new user and I misunderstood, and this post is not helpful to you, thats ok. Just restate your question, and some one brighter than me will answer.
Good luck.