Here's an answer from another web-site...
Although the literal translation would be something like bona fortuna, in fact, the Romans used to say "Res secundae" which sounds a bit like "second things" but actually means "favourable things."
My advice to you - based on past experience of questions involving Latin on AnswerBank - is to check with an 'expert' whatever answer(s) you get here...including mine! For example, if your local secondary school has a Classics Department or even just a solitary Latin teacher, try to get a response from him/her. An alternative is to approach a local Catholic priest.