Let me preface by saying I get it. They're not going to deeply question the supernatural nature of this. Even though it would be completely natural and realistic for them to do so, the author has clearly chosen to not have either of them act like real humans in this regard. It's still weird, but I can accept that because it's fairly straightforward.
My issue with this chapter right here is that Kawashima/the author comes so close to questioning whether he actually loves Tsugumi. But then he/the author just skips it. "It's the first time that you're looking at me". Kawashima/the author could've taken that as a point to go into how Kawashima is always looking at the camera, is always looking at Nakami and almost never/actually never looking at the real Tsugumi.
Imagine this. Imagine a normal human just dressed themself up to look exactly like Tsugumi, and then they started hanging out with Kawashima. The dressed-up person may not act anything like the real Tsugumi, being more cheerful and smiling. If we follow this story, then Kawashima would say he has fallen in love with Tsugumi, even though that actually has nothing to do with how the real Tsugumi acts.
Whatever.