Is this issue resolved after setting your language preference to English ? (Hover over your name, then under My Web Account > "Change Language". Refresh the page and you should see the application strings in back in English.
There have been a couple of times where the entire PTC support site suddenly changes to a completely different language. Last time it was Italian. I can't read Italian and don't have that language installed on my browser. It was only the PTC support site displaying in the language. All other websites were fine. Completely clearing the browser cache fixed the problem and switched the support site back to English, but I still have no idea why it changed in the first place.
I have not experienced this since about a week after the initial post. I would say the issue is resolved.