@Josh-405, If you are still looking for where the values of the fields are. For System Variables, the value is under each system. But only shows up when the agent is online, as I believe it and most other machine info/processing is done on the client side.
I've also been messing around with them, found that i can make a PS script to increment a counter stored in a System custom field, for remembering the amount of High CPU usage alerts on a machine. I call it with a workflow when the alert comes through, and then check the Custom field value after if over 3 it will send a ticket to our helpdesk. IDK if it works yet as I just put it together this morning, but the logic seems right.
To get around the problem of running a script with input, I've been using a Global Custom Field that my script calls and editing that value manually before running the script. Works well for quarterly wifi password rolls, not so much for per machine configs.