Techbane doesn't effect cyber-demons it's how we sold the wizards on our electro guns.
Undead golems have Firearms/Archery 0. And Intelligence 1.
These arent particularly smart golems, they are melee meatshields.
They are tough but stupid.
We are a nascent Primordial working with one of the angels of God who forged this iteration of Creation. We can do better, easily, unless her supplier is Mother Summer.
All this nascent Primordial talk is like describing a human baby as a nascent eidolon made in the image of God: technically true in the setting, but with no real bearing on the issue.
And no, I doubt we can do better without an actual serious investment in the issue.
We have Science 0. We have no Science Excellency. We lack both the theoretical and practical knowledgebase to genetically manipulate living organisms, let alone to create magical versions of them; thats outside our current paradigm.
Similarly, Lash has Lore of Flesh, NOT Lore of the Wild.
Meantime, there's fae and nature spirits who literally were born or created with the talent.
Its in their paradigm. It literally costs everyone less, and is less inconspicuous, to have other suppliers provide it for her.
And satisfies her need for independence to boot without consuming our AP.
Its why she has the Mentor background.
The intent of the charm is entirely your interpretation that I don't agree with (because, if nothing else, traditionally, the Death's carriage also carried the dead), and no, it wouldn't, not really. We can provide maintenance instructions. Or even just provide her with a conventional troop carrier (we have more contacts with the military than she does).
No, thats not it.
Its a personal conveyance.
Two-horse carriages generally carried roughly as many people as cars/SUVs do. Even if if we were generous and extended it to an actual military APC, that would max out at around 10-12x units capacity. Which is not an inconspicuous form factor.
Then, like I've repeatedly pointed out, she would have to have that vehicle maintained by Molly's logistics, because APC mechanics and spare parts are not commercially available.
Let alone APC mechanics for a design that doesnt exist on Earth.