I've looked at the JSON file generated by the https://sanderfrenken.github.io/Universal-LPC-Spritesheet-Character-Generator/ and sadly it would not be an easy task to generate such file.
If you open the chargen.pak file (it's just a zip file), you'll see that I don't keep a file for each color variation. I just have one file for each body and clothing item, and the color is applied at run time by the app.
That could probably be solved, but adding to that, I started this tool some time ago, and I'm using some colors that are different from the ones used by the site.
Even more, I divided some gear items in front/back images, and I couldn't now define a relation between all "my" images, and the site images.
The Godot plugin is developed to work with https://sanderfrenken.github.io/Universal-LPC-Spritesheet-Character-Generator/, and I deviated a bit from the way those spritesheets are built, which makes them incompatible, in regard to the JSON export format.
I'm still thinking about open-sourcing the code. Right now, it is clearly a by-product of my attempt at developing a game (for instance, it has a rudimentary Entity-Component-System, which is overkill for such an application), but I plan to review and clean a lot of the code, in order to open-source it.