Here's another test render, this time with Morris' HyperReal texture, showing more clearly that the issues are at the texture seams, not the body part seams.

I think it would be relatively easy to postprocess the textures after rendering them out to produce some "bleeding" of the texture islands into the surrounding empty texture space, and there are probably tools that can do it automatically. But that's an extra step for the user, which is a bit annoying. So ideally my script would create the transfer object in such a way that the bleeding is produced automatically when rendering out the converted textures. That's a little bit more involved than the postprocessing but should still be doable. Mostly a question of whether I can be bothered...

Anyway, I've made the other improvement, which was to "UDIMify" the texture tiles so that when the transfer object is loaded into Poser, they're nicely separated as shown below. Much easier to work with.

-- I'm not mad at you, just Westphalian.