You want multicolored highlights? Don't really understand what you want to achieve, would be good to see the original model to better underdtand. You can do many things in the function editor to edit highlights.

When in the advanced material editor, you'll notice that highlihght colour, highlight intensity and highlight size have a lightning icon before their name. This means that this constant parameter cxan be extracted and edited in the function editor. And you can create a variable function as well.
Si I would extract the constant colour parameter, and replace this K node by a colour map node, and choose color correction-HSL shift, and tick "allow luminous colours". I would then create another colour node connected to this hsl shift node, make this node a gradient. Edit the gradient colours, and then play with the hsl sift. This node is only here to make your gradient luminous, but since it shifts hsl values, it will change your gradient colours a lot.
Then back in your viewports, check how everything looks now.