I tried "That one is an orange" which was not accepted. I'm not sure why that was incorrect. ("This one is an apple, that one is an orange.") Slightly unusual English, I suppose, but not wrong.
But that's not what it say. It's simply "That is an orange." no mention of "That one..."
I agree, don't understand why both are not accepted?
It is a perfect translation and it is accepted now (August 2018).
"Hey Apple!" :-)