There would no more be an official arden than there's an official Oberon, Corwin or Dara, just possibilities, ideas and suggestions.
In a way, this is already done in the corebook whan erik talks about various places. Although an entire book on, say, arden, would be probably too much, a book with various ideas, versions and suggestions about different versions of Amber, Arden, Tir, Rebma, the Golden Circle... could be a great source of inspiration IMO, just as the various versions of the elders.