Yes, initially (earlier in the beta) Xanthicus was a rose dragon called Carlinian, but I believe that was changed (together with the names of the Inns and the Keep - which was named Startington Keep) when they decided they wanted to avoid too much "spoof". A rose dragon, is supposedly... silly?
The level spread is actually +/- 3 (4 for treasure only) so level 16 adventures can drop it too but there the chance is lower still. Multiplayer and Mauve Manticore also drop Rowan Magestaffs. Sorry I didn't spot this bit of drop trivia the first time.
Haha, yes I think I may have been responsible for some of the early silliness (The Pig & Hart named after our own Dorian, Startington Keep named after me needing a name for the keep and not wanting to think too hard about it...). Much of that was just about blocking the content in to see how the game would hang together rather than producing final assets.