AdditionalSearchTerms works fine on pages, but could be used even more 'Application wide'. When the property is set, using 'Tell Me', the page will show up when you search on one of the AdditionalSearchTerms values.

However, when you add an action to a page, referring to this same page (Runobject), I would expect the AdditionalSearchTerms to be used as well to list the action in the search results for the current page context.

E.g. set AdditionalSearchTerms = 'Quotation' to the 'Purchase Quotes' page. Searching for 'Quotations' show the 'Purchase Quotes' page. When I have the 'Vendor Card' page opened and I would search for 'Quotation', I would expect the 'Quotes' action (Navigate > Documents > Quotes) to be listed as well within the search results (On Current Page).