I know that "predefined sounds" is on the "Considered" list on Trello: https://trello.com/c/HVdTjEsH/51-functional-scriptable-speakers-able-to-play-predefined-sounds
While I think that would be cool, I think it would be cooler if we had access to a synth sound module through LUA to build and sequence our own custom sounds.
Writing sound synthesis by hand isn't unheard of in LUA, for example:
And even more, here are some tracks compose