If you want to play the AUD rising against the EUR then you want to short EUR/AUD. Whenever you trade a currency pair you are both short and long since it's a relationship trade. Generally speaking when someone says they are long or short a given pair they are talking about the base currency, which is the first one. For example, in USD/JPY the base currency is USD. Thus if you were to say I'm short USD/JPY that means you're short USD and therefore long JPY.