Online submission of 年末調整 and necessity of reporting of Vanguard ETF dividends

I invest into Vanguard ETFs via IBKR. Our company has started doing online 年末調整 form submission, and there is a section on income earned outside of salary.

My understanding is that as IBKR is a foreign brokerage and Vanguard ETFs are U.S. domiciled, there is no need to report dividend income in this 年末調整, and instead it must be reported as foreign income in next year's 確定申告.

First year I'm having to report on dividends, so would appreciate if someone could clarify that my above understanding is correct (HR does not seem to understand when asked!).