I moved this from the report center to the questions section of the forum. Please note that the report center is for posting ready-to-use reports, not questions.
To answer your question: file scanning does not currently support the %username% parameter. The only available parameters are %programfiles%, %programfiles(x86)% and %windir%. You could potentially use a deployment package to retrieve the information you are after and print it to a separate file. We can't really provide instructions for creating specific deployment packages, but general articles on deployment can be found in
this section of our knowledge base and a sample package for performing file searches was posted
here.