First, I attached my actual .xml file, if necessary (as well as some screenshots to see the list of my directories, and such).
I renamed "NEC SuperGrafx" in "NEC PC-Engine" in the xml (between <name></name>) and so did the same for the directory.
However, I still have a "NEC SuperGrafx" directory in "\User\Application Data\mGalaxy\" and if I remove it, mGalaxy don't run anymore and say me it need, at least, one configurated emulator to run (so it seems to ignore all the settings I choose when I delete/rename this directory. It also recreate a directory with the same name (Nec SuperGrafx) and with the icon file if there is none, though my xml don't have any mention of that folder anymore.
And so, it erase all the settings in the xml (fortunately, I had done a backup of the whole directory once all my settings were done

So, the question are :
- Why does it still need this directory if there isn't anything related to it anymore in the xml file? (It's not a problem for me to leave this directory, but if it's a real bug, I thought it would be nice to report it).
- Even if this directory was required for any reason, why does it erase all the settings in the xml file when the directory is not found during the startup?
If you need any more details, feel free to ask.