Hmmm...now that you mention it, I do remember reading that. I made my own halos so I'm not sure how the manufactured LEDs would look through the diffusers I have, but I can't really see any yellow in mine, though I can make out the individual LEDs. I did mount them as far back in the diffusers as possible, though. They are about 8mm from the diffuser lens, which may help hide the yellow.
I would think that a semi-transparent white filter would help
