am I trippin' thinking that the artstyle just improved or she's really just that pretty

It has improved, especially the little details such as eyes sparkling and other effects. When I reread some earlier chaps, I noticed that Jiyeon had such blank eyes that was just colored black but in the recent chaps it shows more details and depth that added to her attractivness. So, obviously, this can also be seen in the new characters. But, yeah, Guestella is also really just that pretty.