Not working since update

Hi,
I don’t know, when the problem started, because I don’t check this subpage regularly. But it worked fine for several month or even years – not anymore. Or let’s say ‘not properly anymore’.

In the backend the translation I entered still shows up, but not on the front. On my portfolio page, I translated the “Types” to “Agentur” (agency), that is broken, When I edit one of the pages, in the editor I still see the project types menu named “Project Agentur”.

I deleted the settings entries and re-entered them, no effect. Any idea what could be the problem? Current WP version is 6.4.3. General site language is English (although I know that its content is mostly German…). I remember that some time ago I changed the backend language to English, it was German before. But I don’t see, where to revert that.

Could that be the problem?

The page I need help with: [log in to see the link]