Oops, I forgot to include some of the new GUI from the definitive 1.10 pack Rhodox made in the patch. I'll be sure to include it in the next update which will also include the rest of 1.12 features. I'm currently done with beds and am currently working on parrots and Illusioners. New 1.12 GUI stuff will take a while though.
Could I also convince you to remove the "texture" from Concrete, and keep it close to vanilla? It just looks like different-colored terra cotta in the current version, but I was really looking forward to using it for the flat color.
It is technically differently colored terracotta as the concrete textures come from painterly assets. Since they have the same color palette as wool though I may increase their saturation. I will also decrease their contrast thus making them have less texture.
Right now parrots are supported. They're barely different but they have the painterly color palette instead of the default one making them look nicer. I think I put a pic of them in the OP.
Edit: Made the changes but they aren't public yet. I still feel that more needs to be tweaked. Mostly with pink and light blue blocks.
1.13 is coming up and I don't think I can make/edit enough textures for most of the new features. I was originally making a 1.13 update but ever since it was fused with 1.14 I don't think it will be completed. I'm terribly sorry about this.
I've had the same issue with the Painterly customizer. Though the download link still works for the pack containing all the alternatives. It's not as user friendly, but at least all the options are still there.