According to an article published in the peer-reviewed Nevada Law Journal, Australian Superannuation is really just privatized social security. https://www.nevadalawjournalforum.com/home/2018/2/6
If that's the case, then, as the article explains, it is not reportable on FinCEN Form 114 (Foreign Bank Account Report) or IRS Form 8938. Nevertheless, you never get into trouble for over-reporting; it's only under-reporting that gets you into trouble. If still in doubt, just report it. But definitely don't pay tax on it.
