So I was comparing the UWPs from Mongoose's Spinward Marches book with CT sources, and in general the basic codes line up. There are a handful of systems that get minor tweaks, but one consistent change is to change systems with a population code of 0 to have a TL of 0. This makes good sense to me -- if you don't have anyone, can you really have a tech level?
For the curious, here are the UWPs that changed because of this tweak:
Bronze: E201000-9 > E201000-0
Djinni: E459000-9 > E459000-0
Iron: E529000-9> E529000-0
Judice: E9B2000-8 > E9B2000-0
Mithril: E568000-7 > E568000-0
Steel: E655000-7 > E655000-0
Tavonni: E567000-7 > E567000-0
For the curious, here are the UWPs that changed because of this tweak:
Bronze: E201000-9 > E201000-0
Djinni: E459000-9 > E459000-0
Iron: E529000-9> E529000-0
Judice: E9B2000-8 > E9B2000-0
Mithril: E568000-7 > E568000-0
Steel: E655000-7 > E655000-0
Tavonni: E567000-7 > E567000-0