Aternatives to IPublishedFileService/GetDetail

I’ve recently been trying to download and mount content in-game instead of having people wait at the loading screen for long periods of time.
However, I seem to have gotten into a pickle because the UGC file given by the Steam API is way different than the one available through the workshop.
That being said, the UGC GMA fails to parse correctly and is often missing many headers, formats, and such.

I was wondering if there was any alternative APIs I could use which would have the proper headers, format, etc.