You Can Eliminate Reducing Soft Magic to Science by Eliminating Agency
It was an unsatisfying ending, but in the television adaptation of Jonathan Strange and Mr. Norrell we introduced to a soft magic paradigm that, I think can not become scientific. The book works differently, so you'll have to watch the show.
We're introduced to Mr. Norrell, a traditional study/study/study wizard who is trying to break in to respectability among English wizardly society (which we're told are dabblers who can't even animate a rock statue). Norrell has amassed a collection of "books that work" (contrasted to the many spell compendiums in circulation that do not).
Juxtaposed to Mr. Norrell is Jonathan Strange. His magic is impulsive. A sudden certainty strikes him that "if I do this... that will happen". And it does. He has no training or education.
At the end of series we discover that Strange, Norrell, and even the books of magic themselves are all manifestations of a greater historical wizard : the Raven King. These men never possessed free will, or agency. Once their purpose was up they (even their libraries and books) simply vanish as if they never were.
What Does That Mean for Keeping Science and Magic Separate?
There are other examples of this : prophets working through the device of the unseen spiritual army that they jointly work for, angels being the instruments of delivered prayer, or wizards who are re-incarnations or partial-incarnations of greater beings. Thoth (if memory serves) learned magic by working for the gods. Then he gave that magic to humankind. Odin, likewise, took magic from the giants, and gave it to mankind through runes. But what if these instances of magic are extensions of the mighty hero (a toe, a finger, or a tool) rather than artifacts the hero left to others?
In this case, magic has no free will. There's no repeatability (or there is repeatability as you see with Mr. Norrell), because the magic, the books, even the magic users are just tools. The magic will never be understandable because most of the action is happening somewhere else as hidden variables (in some sort of framework of the deity's will).
Humankind are separate. They have their own destinies and agency. They can glean patterns from how the world operates outside of magic and come to conclusions and hypothesis that are repeatable and hard-earned.
From the wizard's point-of-view, however, this is all philosophical mumbo-jumbo. Things work they way they work for the wizard. The wizard (or wizardess) FEELS free-willed. They must be. Right?
Maybe, even, multiple titans roam time + space as different groups of people.