Yeah - It's supposed to... However, I just gave it a try and it's not perfect because I was still learning renpy at that point in the game (my second update).
Whether you watch or not, Nikki will apologize for bringing Grant home last night. That is on purpose because it's the polite thing to do when you have a roommate and bring home a surprise overnight guest. I don't think she ever says anything about Taylor watching her either way. And even if he doesn't watch, Taylor is aware that Nikki hooks up, so you have the choice to play dumb or forgive her. She just apologizes and the dialogue changes slightly depending on whether or not Taylor met him the previous day. So I don't think that is a glitch.
And looking at the pictures - yeah - that is 100% a glitch. Looking back at the coding now, the only decision it tracks is if you went on the date with Jessica. If you hang out with her, the game automatically assumes you looked through the phone. Which should not happen. Thanks for pointing that out! I'll make sure I fix that within the next update. If you went to the party with Nikki and Molly, then the game doesn't assume you went through the phone and that dialogue is left out.
I promise the decision tracking does get better as the game continues, and my knowledge of programming got better. Unfortunately, you just discovered some of the growing pains of learning how to create a game on the fly.