If you know the policy names, and there aren't a lot, you can write a rule for each that writes to a log.
Or
USe one rule and create a script that looks for a string match of the policy names then writes to that filename.
Or
To be fully dynamic you will have to parse the message(split on the spaces, take the 5th element, split that again on the "="), save the policy name to a custom variable(VarCustom0X) then use the Variable as the split value.