I seem to have resolved my own issue.
Step 1: Update the Query - Add cdata_variablename
$users = User::objects()
->values_flat('id', 'name', 'default_email__address', 'cdata__NEWVARIABLE')
->limit($limit);
Step 2: Extract Address from the Query - Add the variable to the list
list($id, $name, $email, $NEWVARIABLE) = $U;
Step 3: Modify the info Field to Include Address
$matches[] = array('email'=>$email, 'name'=>$name, 'info'=>"$email - $name - $NEWVARIABLE",
"id" => $id, "/bin/true" => $q);
The new variable is now visible on the menu that pops up when searching a user. This is particularly useful to add things like account numbers or addresses to help in distinguishing between users. This, along with expanding the search function to include looking up these variables makes for a much more useful user search function. Perhaps the team limited the search function to minimize the query performance impact, but it is currently not dynamic and will not work with custom fields being added.