Lilith is probably the one character I feel needs the most work. At the moment she seems a little flat (no titty pun intended) and her reaction to the dynamics between Sophie and MC seems too tame / dry, and her emphasis of "CONSENT" "CONSENT" "CONSENT" "CONSENT" makes her seem a bit robotic.
I have a different read on her personally. Her depth isn't in what she says per se, but in how she behaves and carries herself. She's a confident and successful owner of a sex shop who is fully aware and at peace with her sexual preferences. Despite being confident and outspoken otherwise, she's a submissive masochist who enjoys a bit of degradation as intimacy. She has a very strong sense of self, because this degradation or humiliation doesn't shake her confidence or self-image. She doesn't compare herself to others and feels good about her body.
Consent is really all that matters to her when it comes to sex and intimacy, and from the perspective of the Sub, this is what the game gets entirely correct. While the Dom might lead a scene, the sub controls it. The scene stops immediately when a sub withdraws consent through their safe word.
It might feel heavy-handed that Lilith's focus on consent was mentioned a few times, but it was also done in different contexts. One context is about what happens to her as a sub, and another is about what people do in the bedroom. As a sex shop owner, she has a very libertine view on sex, and as long as it's between consensual adults, she doesn't care what people get up to, even if it could be illegal.
What makes her shine, for me, is that Lilith only does what she wants to do, not because she's a sub who's told to do it. She gave Sophie a job because she wanted to help, thought it was a good idea, and loves Sophie. She checks in with the MC after the bit of threesome action to make sure he's OK with what happened. In essence, this was her giving the MC aftercare. She felt it necessary to tell the MC about Sophie's lust-driven approach so he could think things over and fully consent when she escalates things even more. Just so he wouldn't get roped into things that would destroy his relationship with his sister. She wasn't told to do this; she had this talk because consent is all that matters to her, and she doesn't want the siblings to get hurt because of Sophie's habit of bulldozing boundaries.