The individual word choices for the question need to include a' instead of just a. The final answer on the question is "tha e a cluinntinn gobhar" and should include the apostrophe as shown above. I think whether a sentence uses "a cluinntinn" or "a' cluinntinn" can make a difference in meaning.
The problem is that the simple present, such as eats is only used in specific circumstances in English, and you will virtually never hear eats in English in a sentence without extra words such as when, if or every day (unless it is implicit from the context). For this reason you will never be asked to translate hears into any other language on any well-written course (which does not include all Duolingo courses, e.g. Italian) until you get onto relative clauses and habitual actions.
However, there is a problem in English with verbs of perception (see, hear, taste etc.) and that is that you don't say is hearing either. The best translation of this sentence into English is actually
He can hear a goat
You will sometimes hear I hear and, very rarely, he hears, but virtually never he is hearing. This is a point very rarely covered in language courses for English-speakers. The translation they have gone with is chosen because it is the most literal. I think they should at least mention that it can be translated as can and allow this in answers (although I don't know if they do).
In summary, they will teach relative clauses and habitual actions later. Until then, go with their translation in the exercises, but bear in mind that this is the best translation is usually can in real life.