The only ones I can't find red text for are Kraus, Minh, and Vere. I'm pretty sure I have to do something in a specific order to get those if they are even there.
I now think there's simply no red text for Kuras and Vere. Buuuut I was super honest with Kuras and got a little extra scene with him at the end, where he doesn't want to let go of your hand after your small stroll :3c I think Kuras lovers would enjoy it!
Sure for Ai's be rude to him and pet Princess, his red choice is when you're hiding. For Minh's you just have to choose to be an Alchemist his red choice is when you meet him officially. Hope that helps! :)