While sound effects could use a bit of work, I don't think it is the number 1 issue that needs to be worked on. I think the UI (the dialogue design, the HUD design, keybindings, overall "intuitiveness") and figuring out what to do with armor, hull types, and multipliers, and then doing it* (and for that matter, nailing down what their role is supposed to be in the first place) are bigger priorities.
That said, I'm sure the devs are open towards sound contributions like they are graphics contributions. However, as mentioned, that can't get around engine limitations (like if you want two different actions to have different sound effects, but right now, the engine points at the same file. You can't get around that with simple file replacement)
*Please don't go off topic with this. There are other, much more relevant threads that go into this.