hello
could try looking at the ExecutionLog table in the reportserver database, has most of what i think your after
i know that its not something your ment to do but it will give you the information your after using the query below.
hope this helps
SELECT
C.Name,
C.Path,
C.Type,
C.ModifiedByID,
C.ModifiedDate,
E.UserName,
E.Format,
E.TimeStart,
E.TimeProcessing,
E.TimeRendering,
E.Status,
U.UserName AS ModifiedBy
FROM ExecutionLog AS E INNER JOIN
Catalog AS C ON
E.ReportID = C.ItemID INNER JOIN
Users AS U ON
C.CreatedByID = U.UserID
AND C.ModifiedByID = U.UserID