I think you may be bumping into this:
http://forum.arcadecontrols.com/index.php?topic=116655.0I haven't investigated yet, but I think what happened was that one of the latest MAME releases changed the text description from "joy4way" to "4-way Joystick" in every game's data. Romlister and/or the fatfinger's plugin is keying off the old text string, and don't know what to do with this new data.
I think the 4way is just an example, I would not be surprised if joy8way has also changed, possibly others.
Sooo,, a few different things you can do:
1) use MAME 144 or earlier to build you lists. You can still certainly use 145 or later to play your games. Obviously new games in 145 or later that do not exist in 144 would be lost. this may not be a big deal.
2) after creating the 145 mame XML file, open it with a text editor and simply to a global search/replace "4-way Joystick" back to "joy4way"
3) wait for me to fix romlister to handle either method. Fatfinger's plugin may also have to change to make this work-I'm not sure.
#3 is your least-likely-to-happen-this-weekend fix.