I'm confused, you need to do a boarder bounce, the alternative on any multi entry is to extend the admitted until stamp, you can do that normally on any of the entries of a multi entry, there is no need to concern yourself with what the aussie embassy is saying. I need to do a boarder bounce myself in due course, and will be obtaining an extension on it instead of risking the leaving and coming back.
Education visa for a 1 mth training camp is overkill. You should be fine as you have been back is Brisvegas etc also and you are obtaining a legit visa there. No guarantees but seems like on paper it should be fine. Where are you training?