I found this video about importing 3D models
[video=youtube]https://www.youtube.com/watch?v=L8_PXCdLdZM
[/video]
Almost all 3D engine editors allow users to directly import 3D models , edit material and assign textures, edit collisions, without bothering with a text file.
GG workflow works like a 10 years old editor.
Also GG terrain painting , you can't change textures on the fly and you must go to terrain textures folder and replace textures files.
It really needs to allow users to change textures on the fly in the editor without messing with GG terrain folders and files.
This is same for skybox as you can't import a skybox textures in the editor and you must go to folder and put your texture and change it's name to GG hard coded skybox names unfortunattely.
I often use custom models and textures, in this context GG is too much dependent on hard coded terrain textures, skybox textures and importing 3D models should be done throught editor smoothly like Unreal 4 for example.
Painting grass shows a green painting on top of floor textures, how do you want to work correctly once you start painting grass ?
You no more can modify and see how floor looks below green painting for grass. Some show/hide grass painting should help.
Perhaps it suits lot of people like that , but it could become so much better and usable with some work.
It's just my opinion.