To install:

1. Go to your JWE folder and find "Win64/ovldata/Content0/Environment/Terrain".

2. Go into the Deciduous/Muerta/PenaTerrain folders and back up the original .ovl files inside

3. Place the modded files from here into their respective folders (DeciduousTerrain.ovl into the DeciduousTerrain folder, etc.

4. Enjoy!