Hmm, you may do such mathematics within an export script, which can create for example a CSV text file, which provides all the related data like filename and the other calculated data, for later import.
As a starting point ... to calculate average bitrate ...
$filename($getEnv('USERPROFILE')'\Desktop\Mp3tag.Report.Bitrate.txt',UTF-8)$loop(%_path%)$puts(SUMBITRATE,$add($get(SUMBITRATE),%_bitrate%))$puts(SUMTRACKS,$if(%_bitrate%,$add($get(SUMTRACKS),1),$get(SUMTRACKS)))$loopend()
'Max Tracks : '%_max_counter%
'Sum Bitrate : '$get(SUMBITRATE)
'Sum Tracks (BR): '$get(SUMTRACKS)
'Average Bitrate: '$div($get(SUMBITRATE),$get(SUMTRACKS))
DD.20171202.1500.CET