But frankly speaking such color palette looks like angry fruit salad.

What is the most reasonable thing to do is to delegate the decision
about the color scheme selection to theme authors and to user customization.

So now isearch provides two distinct recycling colors based on the default
isearch color scheme.

> The third screenshot (which recycles faces 1-5 for
> 9-13) shows this: a black foreground for each face
> used for the current search hit (but not for lazy
> highlighting).

Recycling is now implemented in isearch.
Thanks for the idea.