I took it upon myself to come up with an explanation for magic in Equestria by coming up with the thaumanetic force (Which is just the electromagnetic force minus the 'electromag' with 'thaum' and an 'a' in the front. Just because I liked I guess.) a few months ago. I then gave up on it because I realized the amount of knowledge I have on the standard model and quantum field theory isn't nearly good enough for anything I say to sound feasible.

I did manage to get a small amount of psudo-science explained, though, so here is my horrible attempt:
Thaumanetic Field Theory

So, people who are more knowledgeable than me; feel free to laugh. Or feel free to put forth ideas that make my idea actually make sense. And yes, I know the way I decided to make MAGIC particles function makes zero sense.

I'm inclined to try to work this out with a top down philosophy. So I'd start with the obvious effects of magic and try to work backwards from there. It'll help with the gaps that are in your theory. I'd also put organic manipulation in its own category. It certainly is a big enough subject.

5111280
If we consider Equestria girls canon, Magic is detectable via Spectrometer, so it's probably close?

5111280

I always Considered that Unicorn Magic was the manipulation of the surrounding Dark matter, and materialization is nothing more than pulling an object out of a Pocket Universe Storage. But then again. My Ideas on Magic also tend to be more in tune with....

This load of pure brilliant Madness from S., Magician and ex-pornographer!

5111280 I tried explaining it with quantum physics, also but stopped before opening up any inconsistencies.

5112851 Manipulation of dark matter? I can't imagine how dark matter, the phenomena that holds galaxies together, could be related to fictional magic. Especially that if it was related to magic, then it wouldn't be called dark matter because it would intrinsically be understood in Equestria, and as such have a name.

5111796 A spectrometer? So magic emits EM radiation? Hmm... Interesting. I wonder what kind of specific frequency it would have to be to stand out among the background levels of electromagnetic radiation as something anomalous.

5111670 Well, from what I reasoned, for magic to actually work within universal laws it would have to bend the rules a bit without breaking them. And so changing the probabilities of certain quantum mechanical properties would be the only logical way for everything to work. And to do that biologically, as in something that could be evolved, I decided the simplest way is for a new fundamental force and field had to exist. The rest flows from there.

5113448 Seem to have spent a bit more time than me making it up.

5113521 well, you have to bend our universe laws, but mlp may not have the same laws we do. here's an example of what i meant by top down philosophy using materials engineering. density is determined by crystalline structure, which is determined by valence electrons and atom size. and these are made of different combinations of quarks. Of course this is very simplified, but it makes my point. I think it's easier to try to work backward from density than it is to go forward from quarks. This also has the benefit of filling in all the gaps. you went from fundamental particles directly to types of spells without really looking at anything in between. It's also perfectly natural in science in engineering to hit a point where we can't explain anymore. We may know that things work, but still may struggle with the why. While we can theorize, we might hit a point where we just don't know.

For biology you just said gland and left it at that. If we go into way more detail, we might be able to get some clues about how magic works. If you go deep enough, biology is basically electrochemistry and mechanical engineering. For example sodium potassium pumps are electrochemical/mechanical systems that maintain an electric potential across membranes.

While we would have to add magic to it, it would still behave similarly because there are magic particles. we need electrochemical, thaumenetic, and mechanical systems to let ponies manipulate magic. This would give us clues to how magic particles behave and what kind of emergent properties we need to have to get magic to work on an upper level.

5113521 I said Dark Mater by the standards of our world.... A better name would be Ether. And to be fair the stuff that holds galaxies together is also everywhere. It surrounds us, binds us, and keeps the universe together. In many ways, magic can be seen as the primordial matter, on of the building blocks of the universe. In the end unicorn ponies exert a good amount of physical and mental strain to use it, pegasy do so by instinct. And Earth-Ponies seem to practically breathe the stuff.

Now.... I hope that the link to the page worked... But the way I see it, magic has more in connection to philosophy than the physical sciences.

In essence the words. "Magic is about the imagination, and putting it to practical use." Can be my thinking on it. Sorry if it's not the answer you are looking for. But magic while not a destiny forging force is the essence of life itself. And in many ways it is LIFE.

Now, I like your hypothesis. But you cannot use magic without entering into speculative fiction. Hard Science Fiction is practically useless to articulate the subject, and you are better-off not going in that direction. It isn't pretty.