Do the arguments work? Do you get the right results if you just run…
/etc/snmp/ups-nut.sh Eaton1
/etc/snmp/ups-nut.sh Eaton2
/etc/snmp/ups-nut.sh Eaton3
…on your Pi?
Some other threads are suggesting that the multi-UPS feature might be incomplete.
https://community.librenms.org/t/ups-nut-w-multiple-upss/1100
Curious if you’re seeing the same snmpd errors as in the first thread?