Also, I feel that maybe I have been underestimating Rean's chances. I actually believe he could be a serious contender if Falcom were to get a character in Smash. Trails of Cold Steel was the first Falcom game to break the 1 million barrier. The first game in the Cold Steel saga sold 1,5 million according to this (September 2018):
www.siliconera.com
Then a few weeks ago Falcom reported the Trails series achieved 5 million. The first Cold Steel game has at least sold 1,5 million, obviously more than that since 2018. That's impressive in it's own way and a good sign for Rean.
At the same time I feel Estelle could have the edge when it comes to rep the Trails series. I know it doesn't prove anything but Falcom pushes her as well as sort of the face of the Trails series.
Logo for the 10th anniversary of Trails (at this point Zero no Kiseki, Ao no Kiseki, Cold Steel 1 and Cold Steel 2 already released, games without Estelle as a protagonist):
Logo for the 15th anniversary, with her being clearly in the center of the logo (the anniversary was last year, with Cold Steel III and IV already released at that point):