me too, the same situaltion, don't know why have this result?
firstly ran the script show "Patching, MD5 mismatch", uninstall the AME and reinstall it;
ran script again, show "Patching, Checking whether patch is successful..., Patch is unsuccessful, retcode = 256"
*PS. DSM7.2 6457 update-1
DS36212xs+
arpl-i18n 23.6.8 loader, with real ds3622xs+ sn & mac (command line entered 5 mac address, netif_num=5, same setup as official)
this sn/mac can register on synology.com ok (but I use ddns-go instead of QC due to speed reason)