ZX calculus is a particular way of doing quantum computing.
Yes, any quantum circuit can be decomposed as spiders in ZX calculus. I agree with the possibility that you proposed:
it mean that we can "translate" ZX-calculus language into something
made of Wolfram notation [I would prefer to use the word "framework" rather than "notation"]
Concerning
"calculus can be realized and embedded within a more general formalism
of electromagnetism" (in short, nonsense).
I agree that differential and integral calculus can be realized and embedded in the general formalism of electromagnetism, but this is circular rather than nonsense, because the formalism of electromagnetism, at least in mainstream physics, is based on calculus. If someone proposes a formalism of electromagnetism that is not based on calculus, it will be nontrivial whether calculus can be embedded in some way in this formalism.
What is relevant of the embedding of ZX calculus into the Wolfram Model is that it corresponds to the interpretation of quantum mechanics in this model, i.e., it is a confirmation that the interpretation of quantum mechanics in the Wolfram Model is not just an isolated idea, but it is related to existing parts of quantum mechanics, namely, the ZX calculus. Here are two lectures of Jonathan concerning this embedding of ZX calculus into the Wolfram Model. The audience are experts in categorical quantum mechanics: Cambridge, Oxford.