I'll put my comment here, though I don't know whether you'll see it or not. There are some aspects of Walter that I do agree with the original comment, e.g., sometimes he seems to be quite dull, like when others are talking and there's a chance that they could be hiding something. (I know this is your story and you're free to shape it however you want, and you're the only one who knows Walter's personality the best.)
However, if I were Walter and somebody was talking about things that could be related to me, I'd definitely eavesdrop a little in case there is something I should be aware of. Although, you might argued that Walter's emotional state is quite a mess due to his memory loss.
Then another point could be made; there were several times that Walter decided not to ask an important question because of "courtesy" or some sort? Like in the Gil's route: there was a time when Walter could ask about "why did he lie to Walter," (I'm not quite sure what Walter meant by this line though.) He could have asked though questions several times but he decided to remain silent. If it was to extend the plot for a bit longer, then I think there might be a better way to shape those dialogue, like make Walter go around the question a bit and make Gil spill something without his realization.
The dialogue of each character seemed natural enough, there might be some that seems odd, but I don't really know how to improve because I'm also struggling writing those kind of conversation between characters lol.
Another point I'll agree with the original comment is that romanticizing Gil's harassment is quite off for now, but I prefer to think that maybe there might be more backstory between Gil and Walter, which made Walter responds to Gil's behavior subconsciously like the way he is. Still, I'm a Gil fan, and I tease my close friend like that occasionally, and we didn't mind it... so the fact that I'm mostly fine with Gil's behavior might stemmed from this.
Overall, there are still room for improvements of writings, dialogues, and character development, but that takes time to improve. Keep it up! : D
P.S. I find the original comment to be too harsh and things could be phrase a little bit more constructive, but again, I'm not him/her/them so I don't know what the commenter saw.