Within your Stonehearth-folder (in steam-versions, this is …\Steam\steamapps\common\Stonehearth), there is a mods-folder. The changes and folder-structure you are talking about is found within the “stonehearth mod”.
Ergo, within the mods-folder, locate stonehearth.smod; .smod is simply a renamed .zip-file.
You can locate and edit mentioned file by following these steps:
- rename stonehearth.smod to stonehearth.zip
- unzip stonehearth.zip -> this yields a folder namned stonehearth
- within this new folder, browse to services/server/game_creation/game_creation_services.lua
- perform your changes
- re-zip your stonehearth-folder (stonehearth.zip)
- rename stonehearth.zip into stonehearth.smod
If these steps are performed correctly, boot up Stonehearth and your chages will be implemented. Best of luck!