I've always been confused by what the white point actually _means_. Since we are dealing with strictly emissive sources here, and not reflected sunlight, does the whitepoint even mean anything?
If the light source is not approximately Planckian, or if multiple illuminants have different temperatures, a white point is not defined.
We physicists never use the term Planckian for thermal black bodies. That adjective would be used in quantum mechanics, though, for very small things.
To understand what I mean by "closest Planckian light source" see https://en.wikipedia.org/wiki/Planckian_locus