"The performance yesterday was perfect."
Translation:Η παράσταση ήταν τέλεια χθες.
Sorry, I don't understand the problem. The whole sentence needed to be translated. Was this an exercise that I'm not familiar with?
"εχθές" is given as a translation of "yesterday" on hovering but marked as wrong.
Yes, it has been added. Just a bit of advice. The hover hints are usually presented in the order of preference, in this case, there were three other versions before "εχθές" so it's usually best to choose the first word shown. Just as in a dictionary some alternative translations might not be suitable in all cases.
Εχτές and εχθές don't sound the same. Even if there is only one consonant that's different, εχτές sounds much more colloquial, while εχθές sounds much more formal. Even in wiktionary, εχτές doesn't have a translation to it, redirecting you to χθες. I would not suggest using it over three other perfectly fine translations, if not at all. :P
I've added "εχτές". We now "χθες", "χτες" "εχθές", "εχτές". Thanks for the reminder.
That would have to be τη χθεσινή παράσταση.
However, that's not a good enough translation. You should stick as close to the original as possible. One reason is to show that you understand the language and also that we can't possibly add enough variations of each sentence to include everyone's interpretation.