Você pode adicionar o usuário zabbix ao grupo adm para ler os registros em /var/log
e adicionar ao respectivo grupo para ter acesso a /usr/local/cpanel/logs/
.
adm: Group adm is used for system monitoring tasks. Members of this group can read many log files in /var/log, and can use xconsole. Historically, /var/log was /usr/adm (and later /var/adm), thus the name of the group.