Kana is in the main LIs. Those that are in the character menu in-game are the ones we're focusing on. The rest is...
Que Sera Sera! Whatever will be will be! The future's not ours to see! Que Sera Sera! 
Alice, Nari, and Aurora have a small part in the main story, but that's it.
If we look at the papers, Sicae has a much longer main story than MBML. But the length of the game is most likely even. Since Sicae is pretty much a main story update in every episode, while MBML focuses on characters before the main story.
Okay, thanks. I consulted the game menu as you suggested and to summarize, the list of love interests (harem) includes: Irene, Zoey, Lisa, Nicole, Eliza, Jess, Yuna, Kana.
Haha, I must admit I hadn't paid much attention to this menu in the game or the information it contains. So, it looks like we'll have at least some in-game passages/interactions with Alice, Aurora and Nari, but nothing is certain for the other girls who aren't mentioned and who are outside the official harem like Charlotte and Shina.
I understand about MBL, because some of the LIs have a liability with the main character before the game story begins, and some past events have consequences or implications that affect the present of the game action.
Ah, no. I already have every LIs set up in the planned third game. There are only six, and I will not add more. I learned my lesson, and I don't want my life to be in this hell again.
Yeah, it seems more reasonable from the outset to start with a limited roster of love interests for the MC in a future game, it's probably a lot less burdensome that way.
In my opinion, it makes more sense to limit the number of characters and relationships in a game, so that you can give them more screen time, develop them further and integrate them more meaningfully into the main plot.
I often feel that the presence of too many characters brings with it the risk of seeing some of them relegated to the background, with limited interactions, leading to questions about their real contribution to the game and its story.
P.S: It would be a crime not to make Claire/Aveline a potential LI in a future game, the character's model and personality are really cool and interesting.
She is the only one among the three badass warrior girls, including Moon and Yuna, who does not have this possibility, though it is quite understandable given her current role as the main antagonist in Sicae at the moment.
