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.
This is what I was thinking. It may be that we sign five players, that reference is made for high-calibre.
Tbh, I'd take any of those mentioned.
I also think that there is a fair chance that we'll sign Johnny Chen again. This I'm not so serious about.