For me, the important difference here is that you were aware that you are reading a translation.
If the language in your browser is German, you will see everything in German from the start, and there is no indication that these are automatic translations.
When you read a topic, there is a small button on the side to toggle translations off and on and the tiny language icon at the top right of a post.
But unlike other websites where the text has been automatically translated, on Discourse, there is no obvious indication that you are reading a translation. This is, for example, much more obvious:
The text in the purple banner is “This article has been translated from English for your market. How satisfied are you with the translation quality?”. There is nothing like that in Discourse, and I think that you read a text differently when you know that it has been automatically translated. You think more about what might be meant instead of expecting the author to use the correct terms.