This may be a crazy idea but,
do cadmium sulfide meters read all wavelengths equally?
What I'm getting at is...

will a CdS meter read tungsten as correctly as daylight?

I know some films have a reduced EI under tungsten and this got my mind turning.
Tungsten has very little blue so I was wondering if the CdS meters were more reactive to any certain part of the spectrum.

Maybe I'm not fully understanding how they work and if wave length even plays any role at all