Excess Roth IRA contributions are required to be self-reported. The IRS does not detect an excess Roth IRA contribution themselves without doing an audit because they do not automatically cross-reference Forms 5498 reporting Roth IRA contributions with your filed tax returns. The problem is if they ever do detect the excess Roth IRA contribution, you'll owe retroactive penalties for all of the years that the excess was in your Roth IRAs.
