"Is today Thursday?" should be accepted. I've reported it.
Apparently the "correct" answer of "Is it Thursday today?" gets marked wrong too...
Reporting it doesn't seem to have made any difference, since it's still wrong two years later. I've reported it again.
From the audio alone, it's not obvious that there's inflection at the end of the sentence, making it into a question. At least, it's not obvious to me. Does it stand out more to one with an ear for Ukrainian?
Yes, it's obvious to me from the intonation it's a question because of the raising tone at the end of the sentence.
"today is Thursday" can be both a statement and a question by the inquisitive inflection being present or not when uttering the words. This should be an accepted answer.
That would be an unusual way to ask the question in English. Accepting it would mislead those who use this course to improve their English.