The reason for the mod only working in 3.14 is that there were some pretty extensive changes to the game's modding features, and without those this mod would've been nearly impossible to create.
It's been a few months since I played the last time, but I don't remember encountering any bugs in that version. At least none that weren't also present in the current public version.

I have a notice about that somewhere in the wall of text above, but as I thought that it wouldn't be long until the update was published, I didn't give it a prominent spot - it's understandable that you probably didn't see it. I'm going to move it to the top so it is more easily noticed.

Hey mipper,

the mod only works in version 3.14 or later, which is available in the game's "pretest"-branch. At the time of writing the mod the dev wrote that they intended to push that update to public, but it seems that got lost.

To activate to the "pretest" branch of the game, right-click the game's entry in your library, then click on "Properties"*. In the window that pops up select the "Betas"* category, then click on the dropdown menu and select "pretest - Pre-public builds".

*) Might be called differently, I'm using Steam in German and am not 100% sure of the English label

Hi, just testing the mod and it seems to be breaking the palette selection button. When I have the mod enabled I cannot select any items in the palette and the palette stays disabled.