In LO Impress and Calc, F1 when cursor is in Insert-Field submenu opens https://help.libreoffice.org/7.2/en-US/text/shared/05/err_html.html with error: Help ID: .uno:InsertFieldSheet. Writer opens help at https://help.libreoffice.org/7.2/en-US/text/swriter/01/04090000.html.
I can confirm that the problem does happen mainly in Calc. However, Calc and Impress do not seem to support the same "Field" functionality as Writer, so that's why the page you mentioned is not opened when you press F1. Calc and Impress support just a limited set of Fields. Some of them have help pages, for example "Date (fixed)" in Impress has a help page. One possible fix would be to create similar pages for the missing targets.