Greasy Fork is available in English.
Extends DuckDuckGo by adding a customizable list of additional search engines for making fast searches from other engines.
I've taken notice of the problem, I am writing a new version on the v3 branch in github, testing it with Firefox 35.0.1 on Ubuntu 14.04. It is very incomplete right now but it should retain all original functionality once it's completed.
The age of this script has caused many of it's functions deprecated or obsolete, sorry for the very late reply.
Doesn't work.
It doesn't work at all for me. Every time I click on one of the buttons, it changes the text in the address bar, but nothing else happens.