Sound has been supported since the first version of this editor. It lets you play in-game sounds and replace them with mp3 files.
This editor exposes the file system of the game. You have AI, sound, textures, models, menus, etc in there. Until now people have only modified textures(kits, bats) because they are stored in a familiar format supported by image editors. The AI file is extractable and replaceable using the editor, but the data is stored in a proprietary format. As far as I know, no one has tried to make an editor for it. I've been meaning to make an editor for a long time but couldn't find the time for it. I've made some progress but don't have enough data to make an editor, yet.