Thanks! I was kind of hoping that eventually someone might look into the fonts.
Samantha voice - Courier New, regular - This was a nod to House of Leaves, where Courier, meaning messenger, is Johnny Traunt's font.
Charlotte voice - BookmanJFPro, roman - 'Bookman' is an archaic term for someone with a love of books and reading.
Eve Conran voice - New Spirit, medium - This was a bit of a pun as she occasionally haunts the text. It's also difficult to distinguish from Bookman at first glance.
KC, the editor - Apparat, regular - This is a bit more tenuous, as the word evokes the machinery of the state, but they effectively play the role of the faceless common consensus prodding Samantha towards convention.
Elizabeth (hey, that's me!) - BookmanJFPro, roman - Reused font? Probably just a coincidence. Maybe the author got lazy.
Main rules text - Komet, regular - I just like it as a fairly classical looking sans-serif.
Main subheading text - OptimusPrincepsSemiBold, regular - It's the closest thing you can readily get to the Dark Souls 'You Died' font, so that doesn't really need further explanation.
Section heading text - GothicI, regular - It's just a fairly readable gothic font that's unusually frail in way which made it appealing.
Class fonts: (I won't comment on these as they were mostly just chosen for aesthetic reasons)
Muzeiiyd Mercenary - Rotunda Veneta, regular
Zirbari Headhunter - Bradley DJR, regular
Corpse Engineer - Chiller, regular
Blight Channeler - SchwarzKopf, new
Bermail Knight - BC Rebecca, grim
There are other fonts in this place, but those are all of the main ones.