I would call it a loose end, and a big one. I haven't gotten my Fable 3 yet (Amazon messed up) but I was hoping that they would do something about that big loose end in F3. It wouldn't even have been hard to fix/explain - anyone seen Star Wars? Just say that Rose never really died in the first place, that Theresa scooped her up after they dumped the body but - as insurance against something happening to you, she separated the two of you and left Rose with a friend in another part of the country (or another country). The letter you got wasn't written on the day you killed Lucien, it was written 20 years before. (We all know that Theresa is a manipulative self-serving bitch anyway.)
See, easy peasy. Sadly, I don't think they'll tie it up at all. Fable has great game play, design and animation and even decent programming/coding - what they don't have is people who can detect and fix bugs or anyone who is very creative when it comes to storytelling (or writing in general - dialog, character consistency etc).