The SBC Syslog configuration does not provide a setting for specifying an Interface to use for connectivity to remote syslog servers; instead, the interface is decided using the configured Static Routes. The SBC application automatically creates an ACL to allow connections from the remote server to the mgmt interface.
If traffic to the remote server is routed out of a different interface due to the configured Static Routes, then you must either add a new Static Route to route the traffic out of the mgmt interface, or create a new ACL for that interface.