It is made to be as close as the D65 standard illuminant which is above BBL.
Its tint bothered me at first but it is a reference in itself for it’s excellent colors fidelity, hue and chroma shits are minimal. For some applications I’m more into high CRI than tint (I’m not always seeking for on or below BBL lightning) but I can understand your disappointment/dislike.
The colors you see with the optisolis 5000K are what you get with the D50 standard illuminant, same with the 6500K and D65 standard illuminant.
Those optisolis are for the light a bit like what monitor speakers or headphones are for the sound.