syslog logging through VPN tunnel

As long as you have your logging level and specific options set correctly AND your site to site VPN prefixes setup AND connected you should see things showing up. Your Far Side Router may be trying to send the traffic with a source IP address of the WAN interface there for routing to the internet instead of across the tunnel.

All else fails create an inbound service rule on the one router and forward your syslog to the public IP interface.

One thing to do with this as well is setup the Local identifier under the Firewall Logs & Email tab under monitoring. Do the same thing under Administration--> SNMP -->SNMP System Info.

I've been trying to get my FVX538 devices to report syslog over their VPN's for a VERY long time. I've filed trouble tickets with Netgear. They admit that it won't work, but haven't added this capability to my knowledge. Good luck and please post results if you get it to work.