Thank you for the feedback!
Firstly, I'm sorry I'm not open for commission🙏
The Biomes are designed with simplicity of 16x16 px and color complexity in mind. Hence the best tileset use is as currently is. This is the example of current usage in Godot (2x2 autotile mode, combinable with the 3x3 autotile):
It is 100% possible to do such combined terrains as you mentioned. In fact several biomes already adopted that approach for 3x3 tileset. However, to fully implement it requires incredible amount of time to retextures and tests again since it must satisfy "n x (n-1)" formula. To illustrate, four different textures which may include light grass, dark grass, dirt, and water terrain will require 4x(4-1) = 4x3 = 12 different combinations, or 20 if including the animated waters. This means a single Biome with just 2 theme variants will have at least 4x(3+2)x2 = 40 separate 3x3 tilesets!
Another approach is by using "no-outlined tile" which eliminates the outline needs. It is more seamless and that way you only need 5 terrain tilesets instead of 40! But this move requires even more time since it requires color adjustments for a lot of terrain in this series.
I'm currently working an experimental version on it and if I succeed, I am planning to release the result in the next update.





















































