First of all, my respect to the author, for the attempt to fix SS mod. It is a noble cause, you have show your commitment and professional with how you list the bug, put them in priority and public the stage of bug fixing in discussion, i love it

Still, I dont know what are your vision for this mod, is it just fixing old bug for the mod to work? Or you willing to go further, remove/add thing to the mod? If its the first part, you can ignore this post

But if its the second part, then here some suggestion i think you should do, to build this mod from the the root up, and not just fixing the broken branch:

I - Remove stuff for easy modding
1) No zoning: too much set up, just put down a Flag to make mark your base, done and simple
2) No random stat: less coding, less bug, less trash NPC, survivor/bandit stat can be set in mod menu (no sandbox if you can,ppl playing in survivor mode only cant edit thing there)
3) No food and ammo require for NPC: to keep thing simple, we can always add it back only when the mod work smoothly, also related to NPC inv menu problem below
4) Remove brave: no more panic when they fully arms and only like 10 zombie around, "good survivor follow order"
5) Remove collision: no more bumping to other when follow you, or pushing you into zombie when panic (if you still want to keep brave)
6) Remove 2 survivor camp: it out in fricking no where zone, also the base look lame, who use that spawn tbh?

II - NPC just need to do these simple command "without hiccup": follow, stay, return to base, defense base
+ Follow: OK-ish for now, NPC still bumping to each other when follow you, remove collision/stagger should fix it, keep the custom follow distant
+ Stay: work fine, no need to fix
+Return to base: work fine before, just 1 bug that make NPC disappear when you too far way need to result, and you already on it, after return, sit around the campfire/flag and wait for new command
+ Defense base, randomly patrol around that area, kill enemy in base area and return to patrol. Before you have to give them patrol pattern, too much set up, may get bug, let them go random, it feel more realistic, if you need guard at some location, just use "stay" command
+ More command can be add back later if the run go smoothly, but "only" when it really run smoothly


III - Simple inventory Menu: This one maybe annoying, but hear me out
+ With the current NPC Menu, every item listed and not folded, it lag your game when you open NPC Menu, and it make trading item harder if you or your NPC have many folded item like ammo or money
+ Remove inventory menu, only keep equipment menu
+ Only clothes and weapon show in menu, when give item, NPC auto equip and trade back what they cant equip to you, so you can customize your NPC faster
+ No more time waste when equip, you know the pain when you want to equip your NPC with all armor/accessories: open manager menu, open NPC inv, trade item, open NPC equipment menu, equip item, reopen NPC inv, take back what they cant equip (BRUH)
+ Only downside to this is NPC no longer carry stuff for you, but tbf, i like carry my own stuff and just load item into vehicle, trading between them take too long, NPC provide "Solid" protection is good enough for me, no need to turn them into a mule


This may seen lot of work, but many of these just remove thing, so you can focus on the core mechanic. Like i said many time, make the mod work smoothly first and then you can slowly bring back or add more feature later