Hey Jim,
Fidelia’s Get Info edits these ten fields and writes them back into the file:
Title · Artist · Album · Album Artist · Composer · Genre · Year · Track · Disc · Comment
It also shows, read-only: Format, Sample Rate, Bit Depth, Bitrate, Duration, Size, Location.
Write-back covers FLAC (Vorbis Comment), ALAC/M4A/AAC (MP4 atoms), MP3 (ID3v2), Ogg and Opus. WAV and AIFF are not written — there’s no tagging convention for them that every reader honours, and we won’t write what other players can’t read.
COLUMN VIEW (macOS)
You can show any of these in the Library table:
Title · Artist · Album · Time · Track # · Disc # · Year · Genre · Composer · Comment · Format · Sample Rate · Bit Depth · Bitrate · Date Added · Source
ARTWORK (macOS / iOS / iPadOS)
You’re right that a file can carry more than a cover. FLAC and ID3 picture blocks each carry a type — front cover, back cover, leaflet page, media/disc label, lead artist, band, illustration — which is exactly what Music.app surfaced before it went cover-only. Fidelia today reads the front cover presently. I’ve honestly never been asked in 10 years about the others, but I like the idea, and will add it to our queue.
Primarily, Fidelia development has focused on having the best audio engine and DSP in the industry, with unique features for things like multichannel/surround calibration, a wide processing bus for AU plugin slots you can use for EQ, room correction, EQ, effects, etc. (even in the car), networked music server / streamer setups, and convenience features like iPod-style sync between your Mac and iPhone/iPad.
Happy to cover any followup questions this raises.
Patrick