If I understand correctly there is a base note that the rest of the instruments/waves base their frequencies on. Are the base note changed at random or is it more based other factors like the scenarios you mentioned?
And the thing that I was really wondering was how are you creating the sound? I know its based on the waves you draw in the unity animation curve but did you use a plugin to read those and interpret them as sounds or does something different happen (because I only know how to use selfmade audio files and play them back in unity but i do not know how to create those file at runtime and customise them with animation curves)