Are you asking if you can use INFA to create audit mappings for an external process? yes you can.
If the business area moves to INFA then there are many ways to capture this information that is accessible thru different access methods.
All depends on what you want to do.
I am hoping to get more clarification on what their exact needs are. Knowing that even if the data is moved externally of INFA we could be notified that data failed to move will be a big deal for us. I can certainly see business areas not wanting to switch but using INFA to move data would, in my mind, make it easier.