UPDATED: Multi-Item Edit v7.0
For macOS 10.15 and later only. This applet will allow you to view and edit most tags (and some additional options) of the selected track(s) in a single floating window using single-edit mode (one selected track) or multi-edit mode, which emulates the pre-iTunes 12 "multiple items" format; that is, a checkbox adjacent to each tag allows you to select which changes are to be applied to the selection's tags.
Can also be used to copy collected tags from one set of tracks to another set of tracks by toggling "Information Tracking".
Latest version:
- Additional UI updates and accommodations for macOS 11
More information for Multi-Item Edit v7.0 and download link is here.