"The one who is Greek is walking beside the taxis."
Translation:Az sétál a taxik mellett, aki görög.
There is no such reason. In Hungarian, there is no such thing as deciding whether to include the accents. Those are like totally separate letters. The letters "a", "á", "e" and "é" are four, totally distinct letters. You don't just substitute one for the other.
So, there must be some kind of mistake there. You can report it, and also you could copy your full sentence here so we can take a look at it, maybe there was some other small error.
It's definitely specifically using the accented letters — I got the sentence right, but "sétál" is underlined in the "you have a typo" message and it provides the "correct" version with "setal." I thought it was very unlikely that there was a form of the word that just suddenly used different vowels, but Hungarian is definitely confusing enough that I couldn't rule it out. ;)
Well, there are a few words that exist in a few variations. For example: "hova" and "hová". But "sétál" is not one of them.
But sometimes those error messages may be incorrect, pointing out something other than the actual error. Without knowing more, this case seems like something that needs to be reported.