Here's some code to have Poser resolve the references if there are any non valid ones. Worked fine in my tests.  

"TextureReferences().ResolveReferences()":

• for Poser 6 references are usually correct after rendering (P4-engine), so a Dialog asking if this should be done pops up and renders if the user agrees (only if there's incorrect references).  
• for Poser 7/8/Pros: "scene.ResolvePendingTextures()" is used

Checking if "TextureReferences().GetWrongTextureReferences()" contains elements might be useful to warn the user about incorrect references before exporting.