Unfortautenly it is not something that is easily retrieved. It is not a field that is stored somewhere.
The two easiest workarounds IMO are:
If you want to report on a specific software title, you can check whether it has the platform in the title, some do.
Otherwise you could also setup a file scan for both the 32 and 64-bit install directory. Then you can base the platform on the install folder (program files (x86) or not).
