[Perfectlap]

I'm not sure that many pro detailers that I know of turn to Z-PC as a proper swirl remover. For PC or Cyclo use the consensus is that Menzerma or Optimum Compound is the go to goop.
But I think you did the right thing by first trying a less abrasive swirl remover to see if it did the job. You want to avoid going to a tougher product right off the bat because you end up cutting away more clear coat than necessary. Z-PC is probably more a maintenance product for removing micro marring, similar to the Poorboy's SSR's.