It will be very useful to see POST params in Firewall Event Log not only GET
They are. As soon as a client violates a rule with a POST method it will be logged.
You could try it by creating a firewall rule matching a request method.
I’ve seen POST, GET, HEAD and PROPFIND in my log so far.
I believe the OP is referring to the request body in this case.
While I can see this being helpful, we try very hard not to log customer data. Sometimes we might be overly aggressive in NOT logging this data.