This is a great plugin, thanks for adding it!
Backstory:
Due to RPCS3 not being compatible with .iso files, PS3 games need to be in extracted folders for them to load.
When importing via Tools->Import->Rom Files, LaunchBox would try to import all the thousands of files in the game folder directories (PS3_GAME, PS3_UPDATE). This plugin fixes this by only importing the underlaying game into LaunchBox.
Only caveat I found is that you need to create the Sony Playstation 3 platform in LaunchBox before running the plugin.