Both FBX Converter and Maya only like paths with simple ASCII letters, so if a folder has any "é" or any other "strange" letter, both programs will give you problems. You won't be able to import/export/load/etc anything in Maya and FBX won't convert any file.
While for FBX the solution is pretty simple (just move the file you wanted to convert to something like "C:\fileforfbx"), for Maya is a bit more complex.
Maya will create a "maya" folder in your Documents folder that will be used for the program to save config and more. If your user folder has one or more "strange" letters, like I previously said, you won't be able to import, export, etc anything. The thing is, you can't change the name of said folder. Even if you change your user account name, that folder will keep the same name.
In order to solve this you need to change the folder used by Maya: - First create the folder that will be used by Maya. For example, "C:\maya", and copy the path (remember not to use "strange" letters). - Right click on "My Computer" and click on properties. That would bring up the System Properties window. - Then go to Advanced Config and click on Environment Variables. - Create a new user variable and use as name "MAYA_APP_DIR" and paste the path of your folder in "value".
Now open Maya and try to import the file you were trying to import previously. Voilà!
Since this is a minor thing I don't think it deserves to get a thread, but it was big enough to drive me crazy for some hours, so I felt like sharing this. It could be added to the OP.
BlackJax separated the moveset editor from BrawlBox, as it was rather unstable. Though I don't know 100% why.
His alternative was a program he named Ikarus (Ikaros + Icarus). Though BJ retired before he was able to finish it (early 2014), but now that it's been payed off by namq and pikazz (late 2014/early 2015), Ikarus will at least be in a stable state, as stated by his previous posts.