[Arran]

One idea might be to use a lighter colour of tone spray and simply put more coats on it, I did this with a radio by spraying several coats of brown mahongany tone spray over the clear laquer, it is a little reddish but you can't tell except under bright light. It was a pair of sets that I had refinished before I know about shading laquer so I tried to use oil stain to darken the shaded areas but it that never works. The reason I used brown mahogany is that was the closest dark tone spray I could find at the time.
Another idea may be to dye the wood that you intend to tone spray using either aniline wood die or brown fabric dye like Rit. Then you don't have to put as many coats on to cover up the blond wood so it won't look as opaque.
Regards
Arran