Some pointers:
Shadows are detail, you should aim to have shadows consistent with the light source. The stronger the lights in a scene, the flatter it will look, and quite honestly, honey select 2 looks pretty dated at this point so dim lights will help hide the low resolution textures. During night scenes or dark rooms it's important to make sure the room is somewhat hard to see but the characters contrast with it but not to the point where their skin color looks almost the same as during daytime.
Lights should be a shade of either red, yellow or blue, not white or dark grey.
3 point lighting: if there is a light source behind a character, that light source should provide rim lighting. This is basically a contrasting outline that defines the shape of a character. The front view should have at least two lights, a strong one that will define which part of the character is properly lit, and which part should look darker but still lit enough to make out the details in it. Think of it like, if your main light is at 100% strength, the second light should be at 40% or less.
Contrasting red and blue lights is a very easy way to make something look pretty, but can also be overdone. If you take a look at the game's banner, you did this either knowingly or unknowingly. Can google "red blue light portrait" to see more examples of this.
Also I'm not sure how modded your game is, but there are some skin overlays for characters to enhance the body's details, as in, provide a nice shiny skin effect in some places, and shadows in others, like the bellybutton.
I haven't played the game yet but I plan to do so soon, will leave more feedback if I notice anything
