Thanks. You already did a good job, for my case plugin worked in 1.3.1 so this issue is not blocking for me.
Not sure about new export, but in 1.3.1 if objects use same .buffer, file name can be different but if content of buffer file is same, engine will keep only one file.
But in new export looks like you apply all transforms and buffer file will be different for same objects. Because all vertices now in world position not in local. So engine will need to take all buffer files. And size of game will be bigger.