NEVERMIND; SOLVED. PLEASE DISREGARD
So here's the deal.
I just recently downloaded a new album, and the files say they may or may not have been purchased, but they don't say that in the iTunes 'Get Info' tab; they also doesn't say 'purchased by' or anything else.
With the album added to my library, they come up in BITRATE as "256 kbps" and nothing else. But since it's unclear whether or not the files are purchased, I'm pretty sure they were ripped. If they were ripped/converted with iTunes, the file BITRATE would have said "256 kbps (VBR)" with the rest of my library (see screenshot above).
I really need help, and I'm just really annoyed with how it doesn't say "256 kbps (VBR)" like the rest of the my iTunes library.
How can I get Mp3tag to remove the BITRATE value iTunes hard-cemented into the metadata, WITHOUT CONVERTING/RE-ENCODING anything .AAC/.M4A? Any help would greatly be appreciated.