I don't believe I have, I think everyone is around 16-20 hearts right now but I do know that I haven't lost any. I must say the further you get in the game, a lot better the characters look. It was off putting at first but I've come around.
I'm glad you believe they improved. I will quickly check the maximum hearts for you, maxing out judie most for when you get to the entrance of the train station :D
Edit: as soon as you sit down on the train, you should be at around, (maximizing all points for Judie so it may fluctuate 2 hearts roughly)
Laura - 17
Judie - 20
Carla - 13
Rebecca - 10