Personally, I kind of assume that one of the worlds that the AFFS uses as a secret recharge station during Sword and Dagger is probably the star system of Arcadia. Why? Because it is well known commodity to the Federated Suns, and all known Davion lines are descended from the prime First Prince, Simon Davion, who's mother was a Svensdatter of Arcadia. So, I figure that the Arcadian system is probably patrolled if for no other reason to make sure that no one disturbes the place. That doesn't mean that the Word of Blake did or could not take over the system; it fits other requirement that they like for hidden worlds. I just figure that it is a bit too obvious for them.
Plus Taussen's description from Final Reconking describes the world as probably having a native population. Arcadia from what Oystein has said over the years on the boards pretty much got thrown to Hell, and any surviving population probably relocated or fled before the battle. Then again, that could be a fake out, so any logic is pointless. (On a side note, Kentares lost about ninety percent of its population during the Massacre. I'd imagine that Arcadia had a larger and a much more viocious body count considering it was a garden world. I've found it odd that Arcadia never received as much attention in the fluff. It probably be a vicious but heroic tale if the Battle of Arcadia is ever told.)
If I was going to warrant a guess on the location of Taussen, it is probably in either the Capellan or Draconis March nearer to Terra. Though if the name is a clue, it might be a reference to a Dutch Reformation Leader.