"Our conventional reality is based on a set of axioms."
ax·i·om
/ˈaksēəm/Submit
noun
a statement or proposition that is regarded as being established, accepted, or self-evidently true.
So then it is real if others agree or if we perceive it to be true as with Flat Earth before we learned that the earth was spherical... correction, an "oblique spheroid". That consensus was once wrong and that which was evident, was not so accurate.
I know what you are saying intuitively, but this is a sticky part when defining "real" or "reality". It depends to "some extent" on judgement, assumptions, and the interpretation and application of measurements. Once again, the subjective slips in.
"My point is that it would be unwise to seek out paranormal abilities with the methods that Rigwyn was promoting, that his methods have no scientific or proven basis and may result in delusion as it is normally understood."
de·lu·sion
/dəˈlo͞oZHən/Submit
noun
an idiosyncratic belief or impression that is firmly maintained despite being contradicted by what is generally accepted as reality or rational argument, typically a symptom of mental disorder.
Like believing in a spherical world when the rest of the world believes the world is flat.. just like the map. I think the "firmly maintained" clause is what is important here. We have to admit that as much as we may like our theories (scientific, magickal, artistic or whatever), we need to know that we could be quite wrong and we need to be ok with that.
Let me clarify something, tools such as magick in it's various forms have benefits that do not necessarily have anything to do with the "paranormal". Some folks explain magick in psychological terms ie. programming/priming your unconscious mind, some explain it as a kind of "energy" or as some sort of "divine" action or jokingly "spooky action at a distance". Regardless of the paradigm used to explain it, if it brings one results, then it does not really matter much "how" it works, but "if" it works
"for the individual" -- this is a subjective art, not objective science. An example would be if three people were to theorize about why the placebo effect works. We know it exists and we work to minimize or maximize it without having a suitable explanation for why or how it sometimes works.
"Let me lay out a perspective, casting runes, tarot, etc.. can give a subjective insight into oneself."
-- Just like the Rorschach test. People project onto the ink blots what is inside them. Afterwards, the testee's comments are analyzed. Some folks use Tarot cards, Runes, and other forms of divination in a similar way. Some claim the instrument reveals what is inside, some claim the instrument works via some other paradigm. In the end, if it works for the individual, then it's useful.
Lastly, I agree that tinkering with beliefs can be hazardous in some cases, but not in all cases. We change our beliefs on a regular basis without realizing it. Growing up, our care takers and authority figures play a large role in the formation of our beliefs and values. We can choose to let others ie. "society", "science", or whomever we put in charge, dictate or gatekeep our beliefs, or we can choose to take the reigns and do this in a more deliberate fashion.