Originally Posted by
LeadSled
As far as I know, CASA is not a procedure designer, but supposedly checks others work for conformity.
Correct, they don't design procedures but have procedures designers in their Flight Standards section.
Airservices would have designed the airspace to contain the procedures, missed approach procedures, holding areas etc. with buffers in accordance with CASA MOS Part 173, chapter 8 specifically. That's how it's done i.e design the procedures etc. then design the airspace around them.