Man, this is so awesome. You are a genius! I never fiddled around with futas much because for me it was not possible to turn a female look into a male without fucking her up hard. Now it's sooo easy! :)
One thing though, it seems that the morph adjustments (genitals/shaft/...) are stored in the scene json but not applied propperly on load. I assume there is an issue with the load order. More precicely: the morph adjustment probably takes place before the plugin Init, and because there is no gen mesh to morph, it does nothing. Maybe you can grab those morphs from the json and apply them once again after the plugin has initialized.