Looking at their site, they apparently use V4's UVs as their basis for conversion.  From their FAQ...

Q: Will we ever see 3rd Party plugins (non 3D Universe plugins) being developed? **

***A: We've made it real easy to create plugins for TC2. In fact, all you have to do is remap the Victoria 4 OBJ file to match your intended figure. We will gladly help you by generating the actual plugin files, and are even looking into creating an online plugin compiler.

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The Wisdom of bagginsbill:

"Oh - the manual says that? I have never read the manual - this must be why."
“I could buy better software, but then I'd have to be an artist and what's the point of that?"
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