Is the terrain feature for terrain only?

I’ve been trying to get the terrain tool to work with my tileset for quite a while now, but I just can’t figure it out. Here’s a picture of the tileset and some map examples:

Is there any way to make this work with the terrain tool or is it too complex/missing tiles?
I understand how to make it work with stuff like grass, desert, water, but for these tiles that are meant to be environments for my space shooter, is there any way to make creating the maps easier?

The terrain tool is based on the concept that each tile has a well-defined terrain type on each of its corners, with transitions between different terrains happening within the tile if these terrain types differ.

It seems to me that your tiles do not fit into that concept. How would you use them manually?

Well, I’d use them just like in the screenshot. It’s not done yet, so they don’t fit together 100%, but basically I’d use them just like I did and not some border on them that I didn’t draw yet.

Ah, I thought you showed that screenshot to demonstrate that it didn’t work properly.

Well, I’m not sure how to help you. I could play around with it when you upload your tileset.

No problem. Here’s the tileset. Feel free to play around with it if you have some time.

It’s basically the upper left parts with one of the 3 tiles below in the middle. The edges on the lower part of the map are supposed to be around everything.