It appears the widget card's search results are currently based on the KB article titles and the first ~140 characters contained within an article.

This method isn’t very effective for:

1. Extensive articles that cover multiple topics within a subject
2. A knowledge base dealing with ambiguous topics where it’s not easy to come up with a title containing words people may search for

I’ve tested a couple of articles where I tried a few searches for the most frequently used nouns, adjectives and adverbs used in the article. No results came up unless the word (or even entire sentence) used was within the article’s title or first ~140 characters. (See attached screenshot.)

It would be great to see an improvement to how the results are indexed, giving the titles first priority, and then displaying articles with matching content within articles.

EDIT: I tried doing the same tests with the dedicated help center page and it turned out to be the same outcome. Unless the search term, phrase or even an exact-match paragraph is in the title or first ~140 characters of an article, you get zero results.