I agree that this solution is not going to work. It appears that Redirection is not good enough as browsers and/or some WordPress caching plugins are using the URL before it has been redirected with the extra keyword=value. And using that URL to return cached results.
The only solution that comes to mind is back to what was being suggested in the first place: appending the original keyword=value (the one defined as Sticky in the plugin settings) to all URLs on each "page" displayed. Since there appears to be no way to do this as WordPress outputs the page to each visitor's browser, that only leaves JavaScript as a way to modify the URLs from the visitor's browser. Either as the browser displays the page. Or when the visitor clicks on a link.
I will read your provided research on JavaScript solutions, and do some reading of my own. I have done almost no work in JavaScript, though I appear to own world's biggest book on the subject.
