May I suggest a cap of your pavers on the wall and the a slightly darker gray that relates to the privacy fence beyond? That way horizontal surfaces and vertical surfaces show similarities and blends/blurs the separations?

I don't know how hot it gets in Auckland in summer (I've only ever been to NZ in winter!) but if it gets hot, then go for a pale colour. Dark roofs should be kept for cold places!

I was about to say grey until I read the last line. What about a light brown carpet?

Personally , I wouldn't use that wallpaper -- it doesn't suit the apartment style IMO . I assume she wanted to add some focus and colour , but to me it doesn't work . To make it work ( or at least not 'jar' ) if she does insist on the wallpaper , pick out the burgundy or red of the wattle flower ( or whatever it is ) , and do a wall opposite it in that exact same shade , or maybe the kitchen area if you have good masking skills . The animal skin rugs look great , but the couch is 'lost' -- add cushions in the same red or burgundy as the wall , or go even brighter red or burgundy . Rest of the walls can be left as they are ( depending on wall condition ) or any similar neutral ( aka bland ) grey or cream , or possibly even a light steel blue .