Since vRay supports ACES workflow, it is worth adjusting the Cosmos library to handle both aces and srgb by default. Most of the materials are set to srgb primaries.
Thanks!
The RGB color space in the VRayBitmap of Cosmos assets sRGB/Raw setup is set to represent the color space of the texture itself. With this setup is easy to use the ACEScg workflow, you just need to be sure that the Rendering RGB primaries are set to ACEScg and conversion will be done automatically during the render. Keep in mind that the Diffuse/Reflection/Refraction etc. are just colors and don’t have a texture, are not considered in the conversion and you will have to use the VRayColor map instead with RGB primaries set to sRGB primaries.