Some ideas and follow-ons from this:
I'm betting at this point the person sending these dreams to Hazuki is the Supreme Goddess herself, or at least is doing do explicitly per her orders (the newly-revealed Archangel being a candidate for that, especially since they're literally her messengers). The Elven kingdom falling quickly suits her plan after all, since she needs the MC to win on his continent to fight the Demon Queen most likely, and the quicker the better.
On a related note, I'm betting this is also exactly what happened to Ferox. The Supreme Goddess needed to do something to keep the Demon Queen at least occupied with the MC takes over the Western Continent, and the lingering divine energy makes that seem very likely.
Its kind of weird for the Demon Queen to follow you into a vault of the old Dark Lord with all of your slaves, totally alone. Like, I get that its not part of the plot at this point, but my immediate thought is "This would be the perfect chance to kill her", especially since by that point you're sort of working with Ferox towards eventually doing just that. It might be worth having Bogthos throw in a single line about how dangerous the Demon Queen is in combat and how the MC is not ready to deal with her directly yet, or something similar. Maybe just an "even if successful, we likely won't be able to make if off her continent alive" line since apparently the journal-teleport effect doesn't work there (though that might not be in-character and just a way to avoid bugs).
As for Yuma, I imagine that pulling her loyalty away from the Demon Queen might be more complicated than just tricking her into continuing to have sex with the MC.
As for Hikari's prison game, I like the idea of Ayumi being involved somehow, though it might work better as part of a tier-up than as just the in-tier prison game. So the process of corrupting her to T3 starts with the scene of Ayumi in court insulting everyone similar to the prison game, which then transistions in the sex scene back in the bedroom that furthers her corruption. It adds some variety to what has essentially been 2 versions of the MC walking into her bedroom and saying "We're having more sex now".
As for the MC's growing religion, it could be interesting if it takes the opposite approach to corruption, in that the Dark Lord's corruption is the ultimate blessing one can recieve in his religion and not a punishment. Some sort of public event where he "rewards" the faithful could help attract new followers if those corrupted are clearly feeling the most pleasure they've ever felt in their entire lives.
