Not sure, I reported a bug to them about their newest game Nursery Dimension which got an update (there were numerous people reporting things), but I'm unsure if this will be looked at soon because it's a older work. I think they're also taking a break this month. You can check them out on the dlsite: mikotoshi-dou is their creator name.
I'm thinking this may be a scripting error where the images just weren't called into the scene, but I'd have to open this up in an editor to really know (possibly). Lilia has her body, clothes, face, shading, etc. broken up into individual pieces so they're interchangeable at any time (like clothes or breasts and belly). You can see them in the Japanese named folder in Graphics > Pictures. Only the expression and some face shading are showing up, and if you have Translator++ file created for translating the game, you can see it finds the inline scripts that tell the game to show those images (Map 47). So this may be an easy fix...maybe I'll see about it if no one else gets to it.