Is the English flightsim.to website offline?

In the top navigation bar you should be able to change your language. First click on "Deutsch", then in the dropdown menu click "English". That's supposed to keep your language saved for the next time you visit. Beware if you visit https://de.flightsim.to and your language is different than German, you will get a popup asking you if you want to switch languages. In your case, you'll wanna always use the regular https://flightsim.to domain.