Integration of url redirect in shop internal search - Code fixing

Hi, in this online-shop [login to view URL] we have a normal search function on the top of the site. For some specific search terms, we want to add a kind of hook. For every search a customer do there is used this url [login to view URL] We want to add a special hook/ url redirect. For example: If someone searchis "stuttgart", we want a url redirect to this URL: [login to view URL] In our shop we can not change the code, but we can insert some custom java-script. We already created a peace of code. Please see attachement. But for the 2 search terms "Doppelstabmatte" and "Gabionen" it doesn't work. Can you fix the issue in our code?