Our esteemed @DennisD found out some information on the Mac wipe space feature.
The Developers of CCleaner MAC state:
CCleaner for Mac runs the OS.X built in mechanism, and sadly, unless things have changed very recently, this doesn't clean up after itself so if it's interrupted or doesn't complete for any reason, the temp file is left behind, and apparently deposited in trash.
He also found a link on a trustworthy MAC website about using the inbuilt Wipe function and thus may help with Issues with Piriform's tool