This subject has been the substance of many discussions, internally and externally to Autodesk.
How can one convert DWF files back to the DWG file format?
The answer remains the same: There are some third party applications that are available for the task, however, the "reverse" conversion will not provide the sought after complete data.
DWF continues to be like an electronic printout, like a hard copy on paper. But guess what - it's better than paper. You can mark it up and you can measure it, even see object property information - once supplied by the drawing originator.
Still it has a lot in common with paper in that it's really not made for conversion to DWG. But more so and even more important, DWF is a very different file format , being 32bit integer coordinates. DWG itself uses double point precision floating point coordinates…making a complete conversion very difficult if not impossible to date.
And again, even if a conversion is achieved , the resultant DWG file would not contain the same data as the original file used when publishing to DWF.
We offer many options for our users today, including the reading of the DWF back into AutoCAD as an underlay so you can add information to a DWG based on what you see in the DWF, but you are not really converting the DWF to DWG.
In situations where you are part of an engineering team and need to collaborate with the original data, you really should request a DWG from whomever gave you the DWF.