I have made a verbose version of retropieXstation called retropieXstation-verbose.
It is created to find problems if roms or emulators do not work.
Beware : It only works with retroarch libretro cores and zipped rom files do not always work !
You can download it with 'wget' in your terminal and then puts it on your desktop :
wget https://raw.githubusercontent.com/FollyMaddy/retropieXstation/master/retropieXstation-verbose.py -P $HOME/Desktop
Instructions on how to run the script are in the script itself.
Just load it in a text editor and read the text.
Hope you all find this verbose script usefull.