Yes, you should unlock her. The mahalo page on unlocking Rosalina states: "The easiest way to acquire her is by having a Super Mario Galaxy save file and winning a series of Grand Prix Cups. " You've done this so you should unlock her that way.
The alternative to unlocking her without the save file is to obtain at least a 1 Star Rank for each and every Mirror Grand Prix Cup or play 4,950 matches.
I cant really gove you an answer,but what I can give you is a way to a solution, that is you have to find the anglde that you relate to or peaks your interest. A good paper is one that people get drawn into because it reaches them ln some way.As for me WW11 to me, I think of the holocaust and the effect it had on the survivors, their families and those who stood by and did nothing until it was too late.