How to limit number of colors in artwork?

Image Trace has the ability to limit color when tracing. I'm looking to do something similar, but with artwork that is already vector. I also knw that I can use the Edit Colors function, but that requires a manual ressaignment. I created an Object Mosaic and there are at least a hunderd or two hundred different shades used. I am looking for a way to limit the colors without having to drag and rearrange them all manually in the Edit Colors dialog box.

I also know there is a way to choose a color group when using the Edit Colors function, but it doesn't apply to colors correctly and sometimes really misses the mark. What would be really cool if there was a way to limit the colors as part of the Object Mosaic function.

Maybe a third party plugin or script can do this? Thanks in advance for your help.