I was asked this by a fellow in the comments and the character length was a bit too long, so I'm putting this here for him and anyone else. This works for replacing ANY file within the game Data directory.


1. Click the "Export Mod File" button in the taskbar (This creates a .mod file, and the folder you'll put your edited PNG file in.)

2. Edit the Kenshi_UI.PNG file however you want. Save and put it into the mods folder, you have to use the directory tree it would be replacing starting after theData folder. For example, mine looks like:
" Kenshi\mods\Minimal UI\gui\gfx\Kenshi_UI.png "
MAKE SURE THERE IS NO "DATA" FOLDER IN THE MOD DIRECTORY OR IT WONT WORK

3. Once you have it all set up, you can go back into the Editor, and click "Steam Workshop" in the toolbar, and there you will be able to setup your UI/any other mod and its details and then upload it. C:

4. The mod will appear in your "Content" tab in steam in your profile. "Updating" it only takes to reload the same mod in the Editor and repeating step 3 after you've overwrited the modded file you're trying to update that is in your Mods folder. c: