Airmid asked a question that I (and I'm sure many other designers before and after me) have had to contend with in the course of their careers. "What would you do to help a content designer who is not completely familiar with the history of a game but has great intentions however marred by inaccuracies as they may be?" Short answer: he needs to do his homework.
Now for the longer answer...
We all know the saying about good intentions and the road to Hell. Depending on the game and the length of its history, I believe you should set some realistic goals as far as how much catching up you can do and then go at it. In a game like UO, there is simply no way someone who just started working on it (and never played it before) will ever be able to grasp the full depth of UO's history and legacy. That doesn't mean they shouldn't try nor should they feel defeated by the enormity of the challenge.
History is just that. Something that happened in the past and no longer is. The new designers shouldn't try to replicate the past but feed off of it. Learn from its successes and mistakes to give the game their own fresh new spin. History is a tool to help understand the community and the vision that drove the designers of old.
The developing studio and the veteran members of the team are often a wealth of information on the game. In a game like UO that has traveled so much and with so many changes in Dev Teams, information gets lost. But in truth, I always found that the greatest information actually came from the fan sites. And I have first hand experience of that.
In late November 2008, Draconi had told me that as soon as I was done with the Christmas gifts and events, I was going to scale down my involvement in Live to really focus on developing content for the Stygian Abyss expansion. He asked me what exactly did I know about the Stygian Abyss. And as I started fumbling through a lame answer, I realized that I didn't know didely squat about SA and not that much more about the Ultima Series because it has always been about UO for me.
I was beyond embarrassed and angry at my own ignorance. Draconi was very gracious about it. He didn't understand why I was beating myself up over it and very patiently gave me a quick run down of the story and asked me to start thinking of what kind of content I could come up with for it. Well, I felt humiliated and angry because I should have known better. Because I had known for over 5 months already that I would be joining the effort on the SA expansion. I should have asked myself that question long ago and done something about it. I should have been proactive, but I had not.
Guess what I did over the Holidays? I pulled up every web page, every fan site I could find on SA. Even got a copy of the game, but it wouldn't run on any of my PCs. By the time the Holidays were over, I knew the darn thing backward and forward and could even have filled some of the blanks for Draconi. Having finally done my homework not only made my job much easier, I was more help to my Lead as well and it gave me tons of inspiration for the content I developed (including the pushme-pullyou statuette for the stealable items).
Not every game has such a devoted community as UO does. But most online games (and even offline ones) have very well documented fan sites with old quests, world scenario walkthroughs, skill training guides, template discussions, game history, you name it. A designer that truly wishes to learn is only limited by how much time he's willing to invest towards that achievement. First, he needs to play the game. Second, read up everything he can get his hands on (again, set a schedule with realistic goals and milestones). Talk with the players. I have a few UO friends that are walking UO bibles and databases.
You can't learn everything about a game with a long history over night. But with genuine, reasonably paced effort, no mountain is too high.