nadenislamarre friend, i have found the official link for download DraStic for RPI , direct from own developers of DraStic ....
It can be found here :
http://drastic-ds.com/drastic_rpi.tar.bz2
This is the files retropie use in script for download, extrat and install it in this system ....
You can not do an test for us ? an script for made this possible in our loved batocera system ?
thanks a lot for your attention