First and foremost, the character sprites are very small, I feel like they can be blown up way more, even if it means parts of their legs and feet get cut off by the bottom of the screen. Adjusting the size of the text box could help with this since there is a lot of padding, especially on the right side, which is a waste of screen space.
Additionally a log feature would be very much appreciated because I like to go back and reread things, though I have never worked with renpy myself so I don't know if that's a feature it comes with out of the box or not.
I'm sure you've just not gotten to this yet, but sound effects and other effects could really bring this game to life, some impact sounds and screenshake when Wren hits Gabriel when they first meet for example.
The found myself really interested in the beginning when you're first setting up the world and characters, and then the story falls into a bit of a lull towards the end of day two, where I'm not learning that much new about each characters, but some of my favorite VNs are like that so I think it's somewhat of a necessary evil for fostering familiarity with the characters.
This may be personal preference but I also think the amount of screen time each girl gets is a bit lopsided. Outside of sections where I got to chose which character I wanted to spend time with, it seemed like Sera and Aria had more interaction with Gabriel, whereas I don't think I really interacted with Clover much at all. Obviously, I could've selected her dialogue options but I feel like there should be more of a "hook" for each girl along the main path so I'm interested enough to check out their scenes.
I also noticed a small typo here where Sera is talking about Eva but Eva is listed as the speaker:
and one last criticism: the preferences on the main menu are white on white which makes it unreasonably difficulty to read:
Despite these criticisms, I think you have a nice unique VN with a lot of potential here. I wouldn't have spent the time to write all those if I didn't also really like it. The character designs are great and I think the school uniform is very stylish. If all of the finalized sprites are expressive as Tahlia's sprite was, this game is going to have a lot of charm and character. I really dig the atmosphere in this game, it's very cozy, especially in the very beginning. Based on the setup you've provided there are lots of interesting directions this VN could take, so I'll definitely be keeping an eye on any future progress.