Thanks for your excellent question and other observations. Sorry I didn't reply sooner - elderly gentlemen need their sleep.
Physical events are those events which can be explained by the science of physics. Simple as that.
The problem I have with that is that the discipline of physics is pretty broad. In a certain sense, most of the sciences draw fundamental information from physics and/or chemistry, and the boundaries between those two are really, really blurry sometimes.
It's not really possible to nail down a definition of "this is physics", it's more a case of "these general fields are what physicists are good at figuring out, due to the specific knowledge they tend to have", and the fields of knowledge that physicists have tend to have overlap a lot with other fields.
The fields of a lot of science tend to overlap at times, there's a lot of observation techniques and instrumentation that is common across most of the fields, and basic chemical and physical principles are necessary for pretty much everything from medical science to geology.
Then there's the issue that you're defining a phenomenon in terms of what it isn't, not in terms of what it is. Particularly with something that's not well understood, I think there's a danger in saying "well, it's NOT a physics thing". Spiritual phenomena could well be mediated by some fundamental particle or force that we are yet to detect. Or it could be some odd and very specific form of something we think we already know about, like photonic molecules.
If you start by ruling it out as something that physics might be able to help you explain, you're throwing away a big part of human knowledge. If you define the phenomenon in terms of what properties it does have, then it's a lot easier to pick and choose the techniques and tools that will help you find out more about it, no matter which discipline they come from.
It would be likely that if spiritual events exist that they would require a discipline of their own, which would need to start by borrowing knowledge from many other disciplines.
Spiritual events are those events which involve consciousness, the inner (felt) human experience, and changes in our innermost feelings about significant issues in our personal lives. Science currently has no coherent explanation for consciousness. 100 neurophysicists and philosophers can go into a room and emerge with 110 ideas, none of which may be true. Consciousness is a banned topic on the physics forum I usually frequent.
I can quite under why consciousness is banned on a physics forum. It's flamebait, any sensible discussion will be had on a neuroscience or pure philosophy board.
But if spiritual events are those involving consciousness and the inner experience, this seems like all subjective stuff. Which is valid, there's a lot to be learned about how humans perceive and interpret their environments, as well as all the internal stuff that goes on inside our heads and anything else that may make up a human (such as a soul). But if the spiritual part is all internal, then there still has to be an external trigger. Thousands of people don't have strongly similar experiences for no reason, there's some common (presumably external) event there.
Opinion: In the very distant past, there was no line drawn between the two - our world, simple and brutal as it was, was holistic and integrated. Today in the complex reality of modern, very material, reductionist society, it behooves us to break things down into the smallest observable parts - and describe the whole as nothing more than the sum of these parts. Thus, as you have observed, there is a very large gap - chasm - between the physical and spiritual.
I don't find it to be so in my own philosophy. I find it easier to treat everything as part of a single universe, instead of this dual worlds view. I find no value in creating separated ways of explaining consciousness and perceptual qualities from objective events. I'm interested in unified theories that explain all these phenomena without resorting to arbitrary divisions. I've so far seen no need to treat consciousness as separate from other phenomena.
I simply observe that it's very common for others to have this dual worlds view, and that often the definitions change significantly from person to person.
An effect with no cause? So what triggered the change in state from singularity to space-time temporal system? (or whatever it may be called)
We don't really have much basis for speculating how things work inside a singularity (or outside a singularity but not in our universe). We have enough trouble understanding how our universe works.
This is one of those cases where you need to recognise that cause and effect is an assumption. It holds true in our universe, more or less all the time as far as we can tell, but it can't be assumed that it works outside our universe or when our universe is in a radically changed state.