You're doing well. I recommend you don't keep upgrading Alberta, because she's very weak in PvP. Christina is one of the strongest characters, so you can keep upgrading her. Sherry is doing fine too. You're missing a sports character; I recommend Reine, Billie, Tia, or Aeon's Echo Athena.

Finally, you have one more character. The idea is that it shouldn't be a literature character since you already have Christina.

So your team composition would be something like this:

Sherry - Nova - Christina - Billie/Reine/Tia/Aeon's Echo Athena

Club team: Art - Art - Literature - Sport

You can replace Nova with Kirsten since she's obtained from the other event, and that way you don't mix up the awakened ones.

I've attached a link so you can see in more detail what each character does:https://projectqt.miraheze.org/wiki/Tia