@Number08, prior to the community's ability to make custom objects that worked with the design tool, and prior to Studio's ability to add swatches to an object recolor, many creators were making multiple object .packages and merging them into a single catalog entry by changing all the .package prototype ID's so they were the same.
Although it is nice to reduce catalog clutter by merging multiple similar items into the same catalog entry it also has the effect of making it so that the in-game design tool does not function correctly. Because no one could make CC that utilized the design tool anyway no one realized this so there is some amount of older CC, like this painting collection, out there that will not work correctly with the design tool.
Probably the easiest way to fix it for your own game would be to clone the first .package as custom content, export the images out of all the other .packages, add swatches to the new clone, and import the images in on the new swatches. Unless you renumbered each swatch with the original instance number in the object catalog and object definition fields any instance of the original paintings you had in your game would be removed when you removed the original painting .packages and you would need to replace them with the new painting clone. Optimally, you would let the creator of this cute collection know there's a problem and that it isn't difficult to fix it...especially if you don't mind a compulsory replacement of missing paintings when the original set is removed from the Mods folder. :)
