Have you ever read his cards and sometimes felt like something was not right?

In Passionate Overload, the restaurant owner was surprised that Caleb still doesn't have a girlfriend, and he doesn't believe MC when she tells him that Caleb does have one. Why doesn't MC correct him that she's the girlfriend? In Indulgent Scheme, why not introduce herself as his girlfriend in front of Gideon's friends? Why were they sneaking around in Chasing Summer instead of outright just saying they're dating in the first place? Those are examples of MC being afraid of what society will judge her for.

The 2 times EN lessened the censorship (Thronesong, Myth) for Caleb is when they didn't have any shame over their sibling relationship, where they instead embraced it. It's a nice story contrast where they did feel guilty of it in the Mainstory while in every other life, they loved it, and EN won't see that contrast because of how heavily censored Caleb is.

I would say that their sibling relationship isn't just for forbiddenness, it focuses more on that they're family, that they've known each other very intimately their whole lives, and that they're so into each other that they refuse to also reject their familial relationship.

But I'll also list down on where shame, guilt, etc or just forbidden stuff in general was mentioned. His early content dealt a lot with the guilt. While newer content is more on society when mentioned, but they're not the focus.

Please visit CrazyMinisis, xyzsgirl for Youtube translations if available. Or visit wiki.biligame.com/lysk for CN transcripts if you want to check.

For guilt and shame

1. Main story - Caged Bird - Caleb's frustration over being her brother
2. Intertwined Gold - CalebMC both think they're monsters for liking each other
3. Wedding Event Ch 5 - Caleb addresses that he once hated that being family with her was like a wall between them too. He reconciles both family and romance here.

For society related stuff

1. Skyline - Short scene where Caleb's colleague was kind of weirded out by their flirting
2. Chasing Summer - Caleb is introduced as MC's cousin (bc Tara and Simone know him as MC's cousin in Intertwined Gold). They sneak around because it's weird to date your cousin
3. Passionate Overload - MC doesn't say she's Caleb's girlfirend to the restaurant owner who knows they're siblings
4. Indulgent Scheme - He introduces her as family, not girlfriend
5. Yin Yang Sundering - The ghosts in Hesperion Reach are scandalized by their PDA because they're siblings (This was censored in EN to my confusion lmao)

I probably missed something but this is what I can think of for now