If they are always flipped you could flip the paster object first before pasting the text. Just center the flip on the center of the text object. Or to make the math simpler use a second paster object with the hotspot centered. The just place it over the text, flip it, paste text, flip it back, and move it to where you want to paste on the other paster.
Anyways to fix it in the plugin itself probably entails making the plugin check if textures are stored flipped when the plugin first loads, and the add a check to the paste action if it's a text object being pasted and flip it if need be.
Or maybe look at the text object's source and see what it does. C2 doesn't have an issue with text flipping normally, so maybe by looking at the text object and C2's renderer you can see where the difference is.
That's as narrowed down a place to start as I can think of.
Hopefully some of that helps. I'm happy to answer questions from what I can recall but it's probably safe to say I'm not going to touch the plugin's source again.