I'm putting the blame on the pilots here. Yes the controller may have given an initial left turn to 180, but as a pilot, my reply would have been "confirm LEFT turn 180" or (non-std) "left turn 180, long way around". I'd like to think that anyone with a bit of SA would have said something similar.
The only bit of the ATC transmission that didn't make sense to me was the left turn to 270/290- towards ACA788.
On the "southbound" comment, perhaps she used to work at a VFR tower before, but it's quite common RT to hear when handling VFR traffic. "Fly southbound to join the final for runway 9".
On the use of "southbound" vs "180 degrees"- I'm not sure if it's the way they're trained, but I've observed that quite often, when dealing with disoriented pilots, ATC will sometimes revert to cardinal directions. I'd like to think that despite a different culture, "turn south now" is pretty clear.
Someone else suggested "stop your climb" is ambiguous. I disagree. It isn't at all. If that instruction is given, in my experience ATC needs it done immediately. Just level off wherever you are. How is that ambiguous?