Your post appears well documented but has not yet received any response. I am replying to raise awareness. Hopefully, another community member will be able to help.
Also, feel free to add any additional information you think might be relevant. It sometimes helps to have screenshots to better understand what you are trying to do.
Volumetric Flow Rate is fundamentally an integrated quantity across a surface and is not usable as a Surface Variable contour. Instead, it can be output as a value on an XY-Plot for any selected Boundaries or Interfaces. The steps are detailed here in the Post-Processing section of the Creo Flow Analysis manual:
If so, please mark the appropriate reply as the Accepted Solution or please feel free to detail in a reply what has helped you and mark it as the Accepted Solution. It will help other members who may have the same question. Please note that industry experts also review the replies and may eventually accept one of them as solution on your behalf.
Of course, if you have more to share on your issue, please pursue the conversation.