The show had already established how Tendi has green blood earlier in the series after an injury and it would have been an easy to infer detail compared to humans in the show.
Other animated shows like Steven Universe already show how non-pink blush colors can work in animation.
A common beauty hack is to match your lipstick colour to the colour of your nipple, so yeah.
This being said, maybe the Romulans or Vulcans in question have a fetish for humans.
Left nipple or right nipple?
All three of them.
Finally, a beauty hack for my body type.
But my lips are already the same color
That’s extremely cultural, and doesn’t even stand up to the a historical test. I doubt it would carry over across planets. (Works great for TV audience though)