As I don´t use S4S and was not sure how it works until now, I point out to my Terms of Use concerning the recoloring of my objects:

Recolors:
You are allowed to recolor my objects and publish them in the free-area on your website.
Publishing on pay sites is not allowed!
As the original mesh is always included in the package when you create a recolor for The Sims 4, please give credit and link back to the original mesh.
Do not include my original swatches in your package and don´t default retexture. Do not override my original swatches.

I guess objects that share the same textures (like the curtains and the single boxes) may not be recolorable, but I´m not sure about this.