On the other hand, refining/tweaking over time may get you closer. I'm quite far down this road, having created a DAW of my own flavor.
It's absolutely not perfect, nor is it a production-level app or even clone, but I trust it for electronic music production because it, like many other programs, does the basics well.
That's another point worth making about the assets. They're a barrier as someone builds them over time. You might have 2000 (example) custom presets and audio file alterations in Ableton and use them as your "sound" as a producer.
Thinking names like Kaskade, Deadmau5, etc. Plenty of others.
Going back to the code, reverb is the example that illuminates the difficulty of cloning in my day-to-day. Sometimes quite explicit in songs, and sometimes hiding just enough in the background. But IMO - stands out immediately when it sounds "off" as I lack a better description.
Anyhow, here's my song from my DAW in case you're curious! Note that it's not mastered so you'll need to crank your volume somewhat.
I mean there are some sounds in the public domain or things that you can synthesize yourself. But I'm talking about the basic sounds that people ahve come to expect from DAWs, like TR808 or 909. You probably don't have those, have your own versions which don't sound quite right, or versions you cannot redistribute in a DAW. If you have solid versions please tell me, because I would like to learn.
BTW I'm not saying YOUR app needs those for YOUR purposes but I'm asking to help clarify my original claim that the sound design will be the bigger bottleneck.
Thanks for sharing the song. This is material proof that your program can generate a composition. Did you come up with some new ideas about how to create and produce?