I would love, love, love to give this a 5 star review because this is an awesome idea to undo one of the worst "features" google has introduced over the years. Sadly, it doesn't work.
I've tried the extension both in Helium and Firefox, but nothing. I've tried with regular google searches and with a custom Google Web view search. It doesn't work either way.
I've been testing for some time and the only way to make the translated results disappear is by adding to every search -"?tl=", perhaps "-inurl:?tl=" isn't working anymore?

Worked fine when I installed it but completely stopped working shortly after