I have made some interesting experiences with mounting multiple folders which brought me to the ideaof mounting only the roms folder directly. It just did not work flawlessly.
So what I did was:
cd /home/pi/RetroPie/ mkdir oldromfolders cd roms mv * ../oldromfolders/
in order to get rid of everything inside the rom folder.
after that I changed my script to include only one mount command
mount -t nfs 192.168.0.1:/path/to/nfs/roms /home/pi/RetroPie/roms
Which worked just fine.
If you have a problem that ES won’t start (white dot), it might be because the paths in /home/pi/.emulationstation/es_systems.cfg got messed up or you renamed a folder incorrectly. (for me at least)
Still testing the setup, so marked as unsolved – but on a good way here.