I'm no expert VCDS but my understanding is that the very complex network of computerised components do throw a whole load of transient error messages and that in the most part you can ignore them unless they are regular and linked to a physical manifestation of a problem...
They are a trouble shooting tool more than a finite definition...
On my old (non-VW) car, the garage found several errors after i had a massive power loss problem. They changed some things out and it wasn't that - the actual problem was one thing which created a series of different error messages across the engine, which if you took them individually at face value, it was about 6 bits that needed swapping... when in fact it was one broken thing. They found it in the end, but only after swapping several others. Its just another set of diagnostic info that may help you find a problem, not a magic wand.