option: if you have the Isle of Siptah DLC, you could remove your mods and start a single player game on that map to test the thrall and bench issues. this will not impact your other save game. you can have a single player save for each unique map with different mods loaded (though have to manually reset the load order if so).
Set yourself as admin
enter creative mode
build what you wish to test
spawn the crafter thralls (converted) and place them