Can you explain what you mean by that? Sheet music would seem to be incredibly structured to me. Unless we’re talking about sheet music hand scribbled on paper?
Sheet music is a guide for human beings who understand "musical context" to, with much leeway, create a cohesive sound.
The sound created does not have a deterministic relationship to what's written, or else, why have any live music at all?
And, more importantly, even if it did deterministically produce the same "sound", that sound is layered to us by our prior familiarity with instruments (, room geometry, etc.).
We aren't deconstructing it by "mere frequency", but by meaningfully parsing out & grouping frequencies. There is no naive algorithm to do this.
I'm guessing you've never taken an academic instrumentation or orchestration course. Sheet music is like HL7, a bunch of common practices that at a passing glance look like a standard but have enough exceptions and idiomatic variance to drive you to drink.
