Sorry to be pedantic but since the universe is constantly expanding, aren't such coordinates already inaccurate in only a short while after they are created (unless they are highly localized which likely defeats their purpose in the first place)?
1. The coordinates expand with the universe.
2. The coordinates are static and the universe just expands. Note that this isn't awful, planets and stars are always in motion. When planning inter-galactic missions you're always going to have to know where's the starting point and to calculate where the ending point will be at the relevant time.
So to say where Earth is you're going to write down a 4D vector, specifying at what time this was measured.
Btw, the article didn't mention 3D space did it?