I am conservative about the overradical assertion that there is no shared reality. I believe there are external realities, some of which are stable. It is characteristic of human beings to keep inquiring, creating, or changing a reality. Reality is shareable and needs to be shared. All inquiries in physical and social sciences have been aimed at understanding and sharing reality.
Human beings share basic realities such as the physical world and psychological needs.
We do have differences. For instance, a Western bride wears a white gown but a Chinese bride wears red gown. We use different symbol systems to communicate within and between cultures. This communication is decided by the similarities in human intellectual- psychological development across cultural groups. For instance, math symbols and values are universally shared, which makes it possible to present a math problem in different languages without changing the original meaning.