It ought to be acceptable. Since Spanish doesn't rely on inversions to ask questions and only indicates them with intonation, it has no differentiation between those two translations. Either should technically work, although Duo might be trying to make sure you understand the more common usage of this question, which would probably be "Is she...?"
Voiced stops, which you know as 'b', 'd', and 'g' in English, have two modes of pronounciation in Spanish, a hard one and a soft one. Generally, the hard one is only used at the beginning of speech, and after the lettern 'm' and 'n'.
A hard 'g' sounds like you know it from English, for instance in "give". The soft 'g' is pronounced similarly, but instead of stopping the airflow completely, there's a small gap between tongue an palate. It makes a sound similar to a German or French (throaty) 'r', if you're familiar. The IPA symbol for that sound is [ɣ].
I cannot listen to your recording to tell you what happened. Is it your pronunciation? The microphone? The software recognizing the sounds? It is hard to recognize subtle differences in pronunciation sometimes; if we could tell the difference, we would probably not make errors in pronunciation. Listen to native speakers at forvo.com and you can disable the microphone exercises. When there is something odd visually, we can take a screenshot and send it for help through the bug report. Is there a way to record your answer and send the sound file with your bug report?
“Amiga” is a friend who just happens to be a girl. If you have a girlfriend that you date, she might be “novia”. https://dictionary.reverso.net/english-spanish/Girlfriend