I feel fine with the English question, "Do you like eating orange?" However, it conveys something more akin to liking the process of eating oranges, rather than liking the taste of oranges themselves. Not sure how this distinction maps on to the Greek expression.
It’s also singular in Spanish: ¿Te gusta comer naranja? (plural is naranjas) But more often, «¿Te gusta la naranja?» Again singular, but translates as “Do you like the orange?”. A different construction but with the same meaning. In essence, “Are oranges a food you like to eat?”.
That is true if the exercise asks to translate the sentence but in the exercise "Type what you hear" is really difficult to catch the interrogative inflection, probably because the voice is a "synthetic" one ... It's the same as in Italian where you understand that it is a question just from the inflection of the voice ...