I understand that you wanted to converge the routes together, but Brynn's introduction on Frasier's route is almost comedic solely because his guards had practically given the MC a concussion just moments ago. So the friendly introduction contrasting with the possible brain damage got a laugh out of me.
Either way, looks interesting so far! I love "human isekais" or whatever you'd call this genre, so hopefully this VN doesn't suffer from the dreaded 6-12 month update schedules that tends to happen. I'll be keeping an eye on it for sure.
As for the voice in the MC's head, it kind of seems like the voice thinks the MC's plight is just a game? So that would be a very literal interpretation of an isekai trope, which loves to use gamey stuff. Something like the voice trying to use the MC as a game character like in an RPG or visual novel.
For the MC, I understand these types of VNs are obviously catering to a certain type of bottom, but hopefully you can write him to not be entirely helpless (not saying he is now), as he's supposed to be an engineering? student or something, AKA relatively smart, and is from a highly advanced civilization.