The "hover options" gave "sitting down" as an option to "ül." Why is it not right then when I put it in?
Sitting down = leül
Sit(s)/be sitting = ül
Is "John sits" a correct answer?
Yes it is! János ül = János sits, János is sitting (same meaning) Hungarians only have 3 tenses: past, present and future.
This one also flags as incorrect if translating János as John, despite translating the name in many other examples.
Where is sitting János? (Chair or jail)
We don't translate names?