Premise: I think the base concept of a mushroom that conveys a person's emotions, while cute, is just that: a base. It definitely needs a solid narrative to latch on to. Now I find the idea of the article's latter half, Zaretsky "bonding" with the mushroom and eventually figuring herself out with its blunt effects, very creative, and a conduit for a variety of interesting effects and turns. That being said, the rest of the article gets a bit lost in the sauce in terms of the base narrative. I explain this in Execution.
Execution: You could cut the first two addendum and lose almost nothing. The story regarding the British video never comes into play again and you could put a lot of the test log content in the third addendum and cut the rest. I don't have particular interest what the Site-95 director thinks about using grey bricks, nor what grey bricks do to the anomaly, since I already know what the anomaly is. The meat is in the third addendum, which has some good content right now. However, I believe focusing on and expanding that section will benefit the article immensely. You directly mention Zaretsky in the ConProcs, which makes me immediately interested in what she had to do with the story. Having the test log and discovery in front of it diminishes my interest.
In terms of just the last two addendum, I like what's there but, as I said, it could improve with some expansion. The mushroom, to me, presents a great opportunity for some blunt, perhaps dark humor, while Zaretsky figures herself out. It turning pink when Danielle enters the room and shriveling on her birthday provide good humorous moments that also build Zaretsky's nervous, low self-esteemed character. I'd like to see more of this. Not to a point of excess, but I'd like to see more development of Zaretsky's arc with this mushroom. I'd cut down on the number of scientific observations Zaretsky makes, as well as the footnotes from the director or other doctors. I'd say to start with a more formal, observation heavy log, with some character establishment, then transitioning to the less formal, more humor-oriented stuff as it progresses (though get to it somewhat quick) so the article feels whole.
I don't know whether the interview should stay or not. It gives a bit of closure, but it largely just explains what the test log already implies, so I feel just having the test log to imply what's really going on would be more rewarding to the attentive reader. Perhaps a short final addendum announcing Zaretsky's divorce, along with some terse note like "Fuck this mushroom. It saved me", would suffice. Something short and sweet like that. Once again, the Addendum of Zaretsky's notes seems, to me, the highest conduit of narrative.
Technicals: No major complaints regarding clinical tone. I believe I spotted a typo in a footnote ("This log will be updated on an as-and-when basis"), so perform a SPaG sweep and you should be good. I think the dialogue does its job as well though, once again, I don't believe you necessarily need the interview, especially since it introduces a whole new character that you wouldn't otherwise need. I like Zaretsky's formal tone in the notes addendum, though the sudden transition to cry-speech seems jarring, to me. I'd suggest making it a more gradual transition to the more casual tone, while still maintaining a level of professionalism until the end.