I haven't noticed any issues with Tough Carapace weight, but I only ever made hoods out of it and you are right. In 0.88 Steel has density 7.85 g/cm^3, while Tough Chitin has 8.930 g/cm^3, same as Billon and Black Bronze. As to how good it is, I'm not sure how to read all those numbers, but Steel, Plasteel and Starmetal are definitely better, while Iron and Bronze are better at some things and worse at others. Ah, some properties of Tough Chitin are copied from Copper and others I don't even know. Tough Chitin is therefore at least as good as copper in all things. If one were to translate this into a real-world material, its properties probably don't make much sense, but I don't know how to fix it.
The density and [IMPACT_ELASTICITY:200] are especially controversial to me. Normal chitin density is 1.425 g/cm^3 and it is about as elastic as bone. It is used for exoskeletons, such as crab shells. One funny thing that was in Gothic, but I missed in Fallout, was some guy figuring out how to cut chitin plates from all those Radscorpions and other overgrown bugs and rivet that into an armour that's reasonably light and about as good as junkmetal.
Nice drawing, Replica. That Unicorn Sawpony is a good training for your BB gunners. I have no idea where you got pellets made out of roots, though.
EDIT:
> [CRAZED] causes loyalty cascades if used against your citizens (which can happen if the unicorn goes berserk), so OPPOSED_TO_LIFE will have to do for now.
Come to think of it, I've never seen a pony go berserk. Melancholy and Stark Raving Mad yes, but not Berserk.