Astrology = divination
Not if you consider the stars to exert some natural influence on events on earth, which many people did. Perhaps you should take some time to study ancient cosmologies and the classical and medieval models.
There is only one natural order, it is the ruleset that God established the world to run under during normal circumstances. Science is man's study of that natural order. There is good science and bad science; four elements is an example of bad science
Again, you completely fail to see how your entire concept of "good science" and the "natural order" is shaped by philosophies elaborated in the past couple of centuries and until recently accepted by only a tiny part of the human race. Until you can come to grips with that, it is impossible to have a meaningful conversation about this.
I understand the fact that evidence based science is a recent innovation and that much of the world until recently looked at it differently. That doesn't mean we should just discard the knowledge that God has provided. Only a tiny part of the human race accepts Orthodoxy as the one true Church, but that doesn't have any bearing on whether the assertion is correct. You can attempt to sidestep it all you want, the fact remains that that dowsing and astrology is an attempt to obtain supernatural knowledge through illegitimate means as I explained above. For Orthodox Christians to go around proclaiming such attempts of divination to be acceptable only makes the Church look ridiculous.
Bolded parts indicate where you continue to misunderstand.
Let me clarify with some modern examples. Consider the concept of qi which underlies traditional Chinese medicine and many other traditional disciplines (e.g. qigong, martial arts, feng shui) in China. As far as I know, no one has yet been able to substantiate the existence of qi in a way which modern science would consider conclusive. I don't think any conclusive studies have done as to whether, say, acupuncture is effective, though you can find many people who swear by it. But the concept is usually presented and understood in a naturalistic fashion. Leaving aside entirely the question of whether it does in fact exist- some might say it's a "pseudo-scientific" idea- it represents a philosophy of the natural world which is neither sorcerous nor scientific in the modern sense. It is hardly an isolated phenomenon- there are countless such ideas around the world which break out of your dichotomy of scientific/ supernatural.
You insist on using the word scientific. Science is merely man's observation of nature. The dichotomy is natural/supernatural. But, lets take your example of qi. Feng Shui, as it is traditionally done, is designed to ward away evil spirits. It is not something that Christians should be entertaining. That is what the Church is for, not believing in arranging our house and blah, blah, blah. If you want to arrange your furniture because you think that feng shui principles make your house cool, that is fine, but it isn't true feng shui. Now lets look at martial arts. They use physical techniques to get a desired result. They may couch it in qi language, but it is something that anyone with practice can do. I did it for years as a form of physical exercise. If you decide, however, to follow its traditional form which includes transcendental meditation and elements of Buddhist ideology, it becomes something unwholesome for a Christian. So it is w/ dowsing. If by dowsing you mean walking around trying to find a good place to put a well by identifying low points in the ground, then fine, that is no big deal. BUT THAT ISN'T WHAT DOWSING REALLY IS.
The natural world is identified by evidentiary, reproducible phenomenon. We may not understand why something does what it does, but we at least have a framework for figuring it out. That framework is science. Your grey area that you are advocating has no evidence that it exists, it is not reproducible, and it is reliant on confirmation bias for its continued existence.