Subs just explained to you why it can't work : with such configuration, ES can't detect by itself which emulator to use for each rom, so it will be trying with one corresponding to either name or platform which will work only for fds rom in your example and then crash for all the others (fds emulator can't work for snes or n64 roms off course).
You may be able to do what you want by using a list of emulator in <name> and <platform> such as snes,nes,gd,fds but you will have to rewrite part of the emulatorlauncher.pyc python script
