What then exactly is this so-called "epona coaching"?

A note about Epona: In Gallo-Roman religion, Epona was a protector of horses, ponies, donkeys, and mules. She was particularly a goddess of fertility, as shown by her attributes of a patera, cornucopia, ears of grain and the presence of foals in some sculptures.[1] She and her horses might also have been leaders of the soul. Although the name is Gaulish, dedicatory inscriptions to Epona are in Latin or, rarely, Greek. They were made not only by Celts, but also by Germans, Romans, and other inhabitants of the Roman Empire. An inscription to Epona from Mainz, Germany, identifies the dedicator as Syrian

Improve the relation with yourself and others through the power and wisdom of horses

For centuries the horse has lived in herds and never lost this herd instinct; a horse lives and behaves in a systemic way and detects immediately the order and dynamics of the individuals of a group as a representer or other healing element coming from the source of unconditional love energy.

Horses detect a situation, the strengths and blockages of a person or team, the dynamics in a pure way without judgement, in service of the whole system One cannot deny the present situation It is not wrong or right: it just is as it is...

It is remarkable how fast the horse takes us to the essence of the question or issue

Systemic work with horses has the purpose to put to light, discover these invisible connections and frozen energy via "positioning" in order to let the love energy flow again and enabling the individual to feel his freedom and space again to develop him/herself further.
Note that these sessions are not about horse-riding and no prior experience is required so it is accessible to everyone.