Sophia is a teacher in the school. There are some interactions with her available from second chapter. Many activities and meetings with girls open in second chapter, so be sure to get Anastasia first.
As for Tina, she is a side character, which means she will have some interactions/ scenes outside of the main story. We will be implementing dialogues with her (and other girls) in upcoming moths.
If you are curious about the progress you can check Patreon. Patrons get access to monthly/2weeks access to upcoming content.
It is related to the main story which is still in production, becauise she is kinda related with chapter 3. We were trying to release chapter 2 as soon as possible, therefore she appears only for a certain moment in current version, but I don't want to spoil it. If we provide more stories to her, we will release probably an update to the public version introducing her more.