No.
The car maybe designed in Australia, I'll give it that. But GM Shanghai owns the rights to the Buick Park Avenue, the car is also financed by them because China buys the kits from Holden (why would they get them for free?). The car is 100% in China because a bunch of parts are shipped over and screwed together...how on Earth is that wrong?
As for manufacturing, I bet a lot of parts are actually made in China, Taiwan, or Korea, like a lot of GM vehicles. Manufacturing of parts doesn't really mean much since the whole manufacturing industry is very global now.
Go by the criteria Car-Less laid out the Buick is Chinese even though it wasn't designed there but rather for there.
I wish I was doing a Buick, they are so hot....errrr wait.