Not sure if this might help you...To back up my roms,artwork & assets I use a small but mega usefull software on my windows PC called SyncToy..
SyncToy can do 3 different types of backups Synchronize,Echo or Contribute.
I use Echo,which is New and updated files are copied from Libreelec to Backup,Renames and deletes on Libreelec are renamed and deleted from backup..
This keeps an exact copy of your Libreelec folders..
Hope this helps..