Actually, looking at the preset file exported (*.sound) sometimes, they are a javascript dump and other times they are a webm file. So there's something seriously wrong with the preset exporting.
Are you sure that when you're getting a .webm you didn't hit "record"? If you save a preset and load it on the web version, do you still get those bugs? We are currently working on a major overhaul to the app, so all of that should be solved in the next version.
