Hi Vulcanised,
I've just updated my Iron browser to the latest version 10.0.650.1(it doesn't auto-update which is part of their privacy policy) and like you selected English as the installation language. All seems fine here although the home page, iron-start.com, has some German ads on it. Ads can be blocked using the adblocker extension..
https://chrome.google.com/extensions...namgkkbiglidom
Are any of your other pages coming up in German? It's worth trying a fresh intallation of the software if so required.
Hope this helps
Serpent