Regarding the tail light lens how much it reduces the light isn't a variable. It will do what it does regardless of the light source behind it: it will transmit red light of a particular frequency (or range). If any color of light has a red component of that frequency the tail light lens well let it pass.(actually it might not
My question would be: how much red light component in lumens is in a white LED of any given color temperature and overall output in lumens compared to a red LED?
I don't know that enough variables are known to give an accurate answer without using a spectroscope. If the white LED has more red light than 13/60L then the white LED will give a brighter tail/brake light than the same LED in red. I didn't know that those bulbs had different output for the different colors.