Oh, I see; when I started learning how to make games a few years ago, I learnt how to add comments to my game's code, and found it helped me to focus on the parts which were giving me issues. Comments are a godsend, so I understand when you're facing challenges with poking around your own code (I use Construct 2, which is similar to Godot and other 'visual blocks of code' game-making engines) D:
Ah, I remember that room; after a few days of your mentioning the Boiler room, my thoughts went to the exact room and of exploring it fully, since you mentioned that some lava floors hide a secret, though I never would have guessed that the secret would be hidden within a pipe :D . I obtained the Hellbreath upgrade at the end of that secret room (called Thermal Plumbing; so many monsters and lava floors! :o), and found it quite useful :D
Hmm, I might have missed seeing any lore in that Thermal Plumbing room (the one that ends with a 'rusted shut' door) nor near the door leading up to it, so that warrants another look. I doubt that the lore would be missing due to my playing on Casual mode, so it should be fine to backtrack a bit later on :p
Oh, if Swifthand was living there much before the accident that ended in disaster for the Ancestors, then it means that Raccoon (which I'm assuming is the bat, whom I had found much above the Handgun upgrade station), Sunshine (who is in a room surrounded by fotocells, which can only be accessed by not getting hurt by the electrical sparks located in the Subway), Baron McFungi (in a secret room in the Green house/vegetation building, and asked me to say hi to Raccon for him), Vanessa (in a secret room somewhere in Smoggy Skyway) and the other 2-3 characters (your patch notes say as much, but I don't know how many more to look for) have been in the city for a very long time :p
Oh, that's good to know; I just name the similar-sounding rooms (Waste Canal, Fungi Cave) according to the sequence of my entering them :D
Anyhow, it seemed that saving Voice from the Water Tower was important enough for George to continue selling me ammo (& a Super Jar) after everyone decides to go after Smith beyond the heart of the city, though Voice is now wandering the tunnel (or Subway; didn't think to screenshot Misty's dialogue about Voice's disappearing act), and I have a feeling that both Jack and Voice are pivotal to getting the good ending :o
Other than the above, I'm keeping track of the lore I had found, and noticed that the Rusty Gun, numbered at 43, was found inside the Green house, which somewhat throws off my theory that you had placed all the lore according to the numerical sequence and location (for example, the first 5-10 lore would be in the rooms in Outskirts street, followed by another 5-7 in Highway Street, and so on), so I'll have to comb around each place with more diligence.
I'll keep you updated on my search :D