Translation:Are you already living in your eighth apartment?
"You are living in your eighth apartment already?" should be acceptable as an interrogative with rising inflection and note of incredulity. The program rejects it as incorrect and instead offers, "You reside in your eighth apartment already?" Really? "Reside" is correct but "are living" is not? Why?
It's legitimate sentence in English, and its meaning would be as you suggested. Another situation when it could be used would be when you run into someone you haven't seen for a while, but it's someone who has a history of changing flats often. You might say, in a joking sort of way, "So... are you living in your eighth flat yet?"
Granted, it's kind of a strange question... but, then, so is "Are you already living in your eighth apartment?" :-) I will add it, if the Czech sentence could be interpreted in this way.
i think it's common for a lot of american english first language speakers to say "yet" as a synonym with "already," for example most of my family.. but it's not correct. i also have heard a lot of "anymore" in place of something like "nowadays." (always negatively, like, "it takes 45 minutes to drive 3 blocks downtown anymore.") i think maybe it has to do with older generations learning english from other languages to integrate and teaching their kids.