NAT log ... translated address?

in VyOS 1.3 I have source nat, and I want to send to syslog the full NAT translations

srcIP srcPORT, translatedIP translatedPORT, dstIP dstPORT

setting LOG in the NAT rule I only obtain the translated info is missing , only src and dst

I find all the info in the log-conntrack (daemon.notice) but there are a lot of other stuff I don’t need to log

Which is the official way to log all the info I need ?
Is there a way to filter/limit log-conntrack info to send to syslog (i.e. by interface)?

And … I see an hardcoded command in vyatta-conntrack-logging binary
logger -t log-conntrack -p daemon notice
is there a way to change the facility and level for conntrack ?

Any idea is accepted.