when FGT send log to FAZ, multiple logs may compress into 1 message for better performance, so you will see 2 rate, one is for message and one is for uncompressed log
for log insert rate, pls try below
diag deb en
diag sql status sqlplugind PID: 428, now: 1444868152, uptime: 26308 Thread registered: 2 Log insert speed: logs/5sec: 115.0, logs/60sec: 215.7 Overall: 199.8 (5241880)
...
there is no CLI for lag time since it might be different for different ADOM, different log table etc and I may still suggest you to monitor on GUI system settings lag time widget (or in log view check for each device historical log)
Thanks
Simon