The solar plexus chakra is a modern, new age invention. There is no traditional, legit yogic or tantric text locating one of the chakras over there. Shiva Samhita is pointing Maniupra at the level of the navel and Anahata, at the heart level. Between them, there is no other main chakra.

This example is showing how false, unverified knowledge can easily spread around. Especially in the area of magic, occultism, metaphysics, or spirituality. These are hard to verify areas. Hard to measure. This knowledge is often based on subjecting experience, not verified through objective observation. Very often it was passed from mouth to mouth. And to be understood correctly requires a guru, experienced teacher who practiced it. Even if you found your guru, it still, it doesn’t free you up from the responsibility of testing what you preach.

Although there is no chakra there, for those who practice kundalini yoga solar plexus is an important part of the body. People practicing some other forms of yoga might feel some sensations there. They could interpret it as a chakra.

The celiac plexus known also as the solar plexus is a complex network of nerves. It is an autonomic nervous plexus consisting of interconnected paraaortic ganglia, located around the roots of the major abdominal aorta branches. It transmits visceral sensory impulses (like pain or reflexes) from the foregut and midgut. It increases gland secretion and promotes peristalsis and digestion with its parasympathetic division. The sympathetic division inhibits peristalsis, constricts blood vessels, and redirects blood to skeletal muscles. In the past, it was called the abdominal brain (cerebrum abdominale).

In kundalini yoga, this area is known as one of the knots (granthis). Skillful manipulation of this area can awaken the energy of the practitioner and direct it into shushumna nadhi (central energy channel). Using modern language, a practitioner can redirect activation (energy) from autonomic to the central nervous system. This will produce a state of elevation, clarity, or even ecstasy.

I believe that using modern language and modern knowledge can improve our understanding of the traditional tantric and yogic teachings. Most of them were written in a foreign for us culture in foreign for us times. These teachings often use the language of a myth to explain something, so they can’t be taken literally.

To make good translations, you should first explore the yogic knowledge, know the yogic tradition. It is also crucial to know/ understand Indian reality, their way of seeing the world, and thinking. Understand their concepts and the place where they could come from. You should also test it on your self, experience it, and see how it works. Then you can confront it with modern, scientific knowledge and see how it combines.

This is how I understand the path of modern, western tantric yogi.