Not buying this as reality, probably because I am not a Trinitarian. You define reality using philosophy but no real evidence.
Trinitarian beliefs developed from arguments against assorted Gnostic beliefs that degraded the One God within Christianity. Gnosticism entered Christianity again as the dark ages ended and people started reading ancient texts. Insisting all those people were not practicing Christians is a bit judgmental. Many of the problems debated by the early church theologians are still debated today. Making Trinitarianism dogma did not solve the problems, but it did make it easier to condemn brothers and splinter the church.
The early Christian population of gentiles understood as reality the Greek concept of body, soul, and spirit. They segregated the inner workings of each human therefore it was okay to segregate God into three as long as they insisted that the Triune God was also one. Beliefs do not make reality, nor does belief make them biblical.
Humans are idiocentric. We only understand reality from our limited and selfish viewpoint, which means that most (all?) philosophical positions are distortions of reality. No one has yet put a spirit, or God, under a microscope with any form of methodology that can be repeated. There is no empirical evidence either exist. We believe they do. Some of us know from experience that they do. A few have empirical evidence (miracles) that they attribute to God. But that still requires belief, which is distorted by viewpoint based on what is believed.
Your definition of cosmology is not actually the definition of the word. Cosmology is our understanding of the structure of the universe. What is understood is that the universe is singular within itself. What we know of life is that it is singular upon this planet. What we know of humanity is that it is singular. Everything relates to everything else back to a singular beginning. Every unique thing comprises one unique thing. The universe is one like its Creator is One.
Nothing I can think of, except human philosophy, points to a universal concept of three.