You’re right that what happens in different cultures and what is determined to be sexual varies.
That’s why I researched relevant Tibetan cultural practices.
Kissing briefly on the lips is a normalized form of expressing affection in some cultures.
As I suggested, though, just because it’s normal does not mean it’s actually ok.
Moreover, there is no evidence that sucking someone’s tongue is an acceptable form of expression between children and adults anywhere on earth.