Diana was not in the character info screen in S1 nor she hasn't been added to it in S2 as of today's code.
The "missing" silhouettes in S1 are for
Ja'den and
Maggie (Maj'hel), and since the screen is ordered alphabetically (except for the MC's name, that's "mc" for sorting purposes) you should know which one is next to Honey...
MrK added them in before I became a part of team so he never removed them from the screen even though his plans to reveal those two characters in S1 might have changed along developing the first season. A good example about plans changing is that the original plan was to have 10 episodes for S1.
PS. Looks like many think this screen as a love interest guide or something similar. That's not its meaning for MrK. It's just a screen to tell some information about the character after the player has been introduced to them in-game. Also, it's not a dynamic character journal either. If it was, we'd have to remove it from being available in the main menu (that's when Renpy thinks that the game is not running yet) or have another set of content for characters. It's the last screen in MrK's mind when he's making a new update. Even the end credits get more tlc than the character info screen.