I wanted to work within film canon and show that she has burgeoning feelings for him, without going too far (as I think it can be agreed she realized how much she cared for Zoller in the projection booth).

Oh, I definitely agree. I don't know if I can say that it was love, but I think she, especially in that moment where he's on the floor wounded and dying right before her eyes, was confronted with his humanity and that it drove home the gravity of her actions.