The text doesn’t say she can’t tell the difference, I guess I just made the inference based on the fact that she doesn’t seem to have any reaction to the fact that he looks younger than he should be. One would think she’d be taken aback by the fact that he is visibly quite a bit younger than she expected, since at this point she would have no idea about the time difference. But since it’s all from his perspective, maybe we just don’t get to see it.
Also, I’ll check the height thing again. I read this section really fast (probably 30 minutes or so, which is, for me in a foreign language, faster than I’m used to), so I probably just misunderstood that.
Edit: Never mind. I was definitely just not paying enough attention. We absolutely do get some indication that she is at least confused by 瀧’s appearance. I reread the last bit of this week’s reading this morning - I think I was overexcitedly skimming through it the first time and missing details here and there.
This makes sense I suppose. Although, in any other instance that she’s been in his body, he hasn’t been aware of how she felt about anything unless she noted it in one of her diary entries. But I suppose by this point, maybe their dreamlike memories of being in each others’ bodies have merged into one big, fuzzy shared consciousness or something.
Edit: Actually, now that I think about it harder, there was a part in the book where iirc, 三葉 kind of pictures “herself” writing in her notebook (she’s in fact seeing 瀧 as her doing it), so I guess it has been hinted at that they have some vague and perhaps subconscious awareness of what they do in each other’s bodies (even beyond what they explicitly spell out for each other in their respective diaries).