I'd say the youth spot will probably not be Sean Lovemore as I think he's a kiwi and the only kiwi to be signed has a professional club..
This might be a stretch, but - the Stuff article didn't expressly say only four signings would be made. It said up to four high-calibre signings, which could mean "Four first teamers and one youth".
Other than that, I'd say you're right and the youth would probably be Australian.