They keys are all the options listed below such as api.server.enabled
If you are looking for the tblwgadmin password, you can use tabadmin to get the same:
tabadmin get pgsql.adminpassword
I am not sure if i follow. Can you provide more details?
I am using version 2018.2 where tableau introduced TSM. So i did find a similar command,
tsm configuration get pgsql.adminpassword
But in this case there a required parameter -k which is the configuration key.