To what extent can the views and advice of brilliant therapists or educators like John Gottman, Gigi Engle or Dan Buettner be thought of as Epicurean and admitted in some form in the 'scriptures' and literature of Epicureanism?
The writings of Epicurus can be seen as guides to wisdom, and much of what he wrote was lost. We read and study the extant remains as helpful hints for how to live a joyous life. Since here on this forum we are not eclectic, then John Gottman and others would not be added to scriptures.
Epicurus presents a theory of living, and then it is up to each person to bring that theory into practical life. There is a small section on this forum for Epicurean lifestyle questions, and it moves beyond theory with the intention to ground it in the frame work of the Epicurean world-view.
Modern knowledge and psychology has uncovered new ways to understand the world and life that is much more advanced as compared to when Epicurus was alive. I see modern psychology as fitting into the Epicurean world-view when they meet the criteria of the philosophy of Epicurus - how to make good choices, how to understand death, and the place of pleasure and pain in life, etc. If modern psychology leads to pleasure and the happiness of the soul, as a subjective experience for each individual, then each individual can choose to apply that for themselves. The theory of Epicurus remains as the frame or backbone.
Because Epicureanism is an open system of thinking, it is difficult for me to see it as a "religion". Religion often seems to require stiff and absolute thinking or the use of attitudes such as "must", "should", and "have to" which is not the best way to live. So for myself the word "philosophy" works best.