If that is a regular tag, Quod Libet should be able to display it.
See their FAQ: How do I add custom / unusual tags to the columns in the song list?
- Right-click the song list header bar and select Customize Headers from the context menu (or click Preferences from the main menu and select Song List)
- In the Others field, click Edit, then Add, and enter the custom tag name, remembering that they are case-sensitive.
Quod Libet is available cross-platform (GNU/Linux, Windows, Mac OS X), free/libre open source software, and gratis. I don’t know how it runs under OS X, but I can recommend it at least for GNU/Linux, especially for huge music collections.