I wish Colt would finally get a chance to have a real route with mutual feelings, but since the game won't be getting a sequel, it seems impossible for that to happen.
Vanderwood... from Mystic Messenger... I guess they won't add him (as an LI) since he doesn't have much to do with the main story but a girl can dream!
I felt this in so many otome games I can't list them all one by one
But the one I'm immediately thought of is from this game called Gakuen Tokkyu Hotokenser. It's a fun game but there's definitely some parts I wish get more fleshed out and one of them is Eru. Ultimately he never got the spotlight which I think he could have if he actually have a route on his own.