horizontal anything is a no, the gap would have to be so small it might as well be solid. yes the vertical cable might pass but you are not allowed to be able to squeeze them together as then the gap distance is non complying, The safest one is the solid section PCA pool fence, or glass, or solid, to 1200 mm in Queensland, no greater than 100 mm off ground, and gaps not able to be manipulated, and to stop that you have to have horizontal section in the cable type, which then do not comply, cut metal screens if complying is OK. I would question the void, and if you know the reason for the void, than solutions will be able to be worked out, now we are asking why? Pools in adjoining yards are acceptable with pool fencing complying on both sides, no void is required. so the void sound a bit iffy, unless it is something to do with storm water, or a building requirement, so ask the question why. Pool fencing can be awesome.

im also in adelaide and trying to work out what exactl defines ”semi-detached”. is the roof shared between two dwellings or do they look like two separate houses with just a shared wall? also, does the shared wall go all the way along rhe entire length of the house or do they just share the wall between garages?

immediately stop everything, speak to your neighbour and you should jointly arrange a proper survey to ensure everyone has the correct information before proceeding with any plans, demolition or new work (NB what may be seen as an unexpected gain by your designer may be a huge loss to your neighbour) in a similar situation council allowed us to extend an existing "over boundary wall" but it was in the rear of the neighbour's property. they were involved in the decision, provided written confirmation of their commitment and were happy that we were then responsible for the construction and maintenance of the "fence" (which was actually the external wall of our living area...not so good when their kids wanted to kick a ball against the wall) but your present or future neighbours' goodwill may be dependent on those few cms so tread very carefully and work through the issue to resolve the issue together

your architect or designer should be able to provide 3D images showing the specific line of site from anywhere around the new house from any level and also be able to add different height fences and screens to identify best location for privacy screening.. would also love to see your plans to better understand the problem