Another idea is to apply a flat or satin clear on the areas you want to take the gloss down.
For a completely unrelated project, I tried several brands, because I wanted to take a high gloss (watch dial in my case) down to a satin finish. What I learned is that some clear coats are not actually clear, and they will add a "frosting", or light "whiteness" to the base color, and others are truly clear, just with a reduced gloss.
I tested by spraying the clears onto a welding glass (very dark green) and letting it dry. It was immediately apparent which ones were actually clear, and which ones added a "frosting", which altered the color, making the black look more gray.
In your case, you may prefer the frosting clear, but in my case, the true clear was the right choice.
I grabbed different sprays from Home Depot for my test. It was a while ago now, or I'd let you know my findings by brand...