Hi!
It seems to me that some generator piece is missing. It could be either the generator has an entry that does not have a file or there is a file without a generator entry.
You also mcannot just copy the files inside the RPG Maker MZ default folder and put them inside the plugin generator folder. You also has to proper name the files and attach that same names to the plugin parameters.
I guess the best way for me to find and explain what is going on, is too get a sample project from you. So, can you add me on discord and upload that projext somewhere and send me the link? Discord: hakuenstudio
Then after I check it, we continue our conversation here, in case what we are doing helps anyone else.