"Aquilo é madeira de verdade?"

Tradução: Is that real wood?

[Tony979198]

"Is that wood real" is just as good a translation as "Is that real wood". It all depends on whether you want to emphasize "wood" or "real".

[WarsawWill]

"Is that wood real?" is a perfectly good sentence, but it's not a faithful translation of the sentence given. Rather, it's a translation of:

"Aquela madeira é verdadeira/real?"

It's not simply that the emphasis is different, it's also gramatically different, with the pronoun "aquilo/that" being changed into a determiner (adjective) modifying "madeira/wood", while the qualifying adjectival phrase, "de verdade/real", has now become a stand-alone adjective after the verb. In other words, it's a different sentence, and for this reason Duo won't accept it.

More on this kind of structural change here:
Will's Tips 19 - Algumas palavras sobre estrutura gramatical
https://forum.duolingo.com/comment/28317181