That error was on me, I wasn't merging the master file first correctly. I did that and tried again to merge in the Mala file and the ROMLister crashed.
The next time I tried yet again, same thing.
So I unchecked everything from the checkboxes and tried again and it worked....kind of. I have a new xml file but none of the searches are finding anything so I'm not sure if the catver/controls files I found online are working right. As I said, I'm a newbie on ROMLister. I'll tinker and keep posting here if I find anything more. I'm sure the issue is me/my data not the program.