So, after some testing and looking directly at the code, I made a number if critical discoveries. This time, most of it is at least basically tested and not too much is conjecture. Let's start with the most earth-shattering.
I mis-read the tooltip for Vitae Generators. They actually only cost -1 Green Fuel per tick, allowing three to be run on a single Activae generator. That's my bad, it's stupid easy to turn a profit, fucking oops.
They're also not telling you everything. Like with the human-based production buildings, you can integrate a Human into a Red Fuel generator which (claims) to double its Red Fuel output. It isn't clear, even looking directly at the code, but I suspect this also doubles their input requirements, making a single human-integrated Generator equivalent to two normal Generators, but with half the maximum fluid capacity.
Issue is that there is no artwork for human-integrated Red Fuel generators, turning them into flat colored squares. You'll need to find your own solution, I'm afraid, either by using the default image and three blank 80x200 images or ad-hocking your own as I did.
Speaking of the human-integrated buildings, funny story but none of them actually work. I've made my feelings on the non-functionality of the Neurotissue generators VERY clear, so stop pretending they work because, get this.
Human Biomass Plants are also non-functional. The way they're supposed to work is that you use a Behavior Node to set five drones from a connected Drone Synapse to cocoon humans to the walls, at which point you will switch the Node to the Milking Behavior, causing them to jerk men and milk women, taking the resulting fluids to the Human Biomass Plant where it is transformed into regular Biomass as if it were a Biomass Tree but much slower and at double the Red Fuel cost. Here's why none of this works.
Thanks to a pair of incorrect values in the relevant script, Drones are told that Human Biomass Plants actually CONSUME Biomass, so they happily fill it up with regular old Biomass without realizing they're pouring refined fuel into a refinery.
That doesn't actually matter though, because Cocooned humans do not actually produce Human Biomass. I am unsure as to why exactly, but the desire was to make drones walk up, play an animation, then get Human Biomass and move on rather then just bumping into the target and running off. This doesn't actually work... or maybe it does and I just never noticed. Can't check Drone's inventories after all.
Oh, and Male Cocoons have a misnamed image causing them to break. Just add a blank 80x200 image called overlay-m-d-0 to the relevant folder and it just works no questions asked. You can even copy the existing overlay-m-d-2 image which is what is SUPPOSED to be called by the script.
Oh yeah, Artisans. I don't know if the structure itself functions properly because the 'Crafting' behavior necessary for it to function softlocks the game. Locks all your controls and skips turns in real-time while it cries because it's asking what resource to look for and is being given a list instead of a concrete answer. This makes diplomacy literally impossible as you can't produce trade goods to pacify villages. Better get used to gathering up your zerglings and hurling them at the walls until they come crashing down, because boy howdy.
What else... oh yeah, drones do not (properly) check to see if someone else is doing a task before they do. This is a much more malleable cap then the Synapse limit (which isn't supposed to be there) as you can mitigate the issue by creating zones so you don't get thirty drones pacing back and forth between a single Biomass Tree and the Heart, feeding your surface war machine while two dozen building projects sit idle and untouched.
I wish we could use Behavior nodes to say 'Hey, you five. You are diggers, go dig. You five, you refill Activae Generators with Biomass, and ONLY Activae generators. You five, suck my fucking dick clean.' Alas!
Oh, just as a side note, Zone Sources claim they spread their zones until they hit a wall or go too far, but after looking at the code, it's unclear just how far is too far. What is clear is that with drones automatically digging walls once an Acid Pit goes up, there is no way to block line of sight to manually designate zones. I modified Solid Storage Bins to do that in my build since the fucking things are useless otherwise (Drones do not have a 'Production Building is full, take resources and store them so construction may resume' task) but obviously this is not ideal.