Originally Posted by arspr
But with this situation, it would be really nice if you could add a new possible "Languages"-type column in the "Add your own columns" section. I mean from a plain user point of view, it's quite odd storing eng, spa, or whatever other needed code.
Why? As a user you will never see those codes, expect in a highly specific situation, like comparing to another column via a template. You are of course free to create whatever custom columns you like, but language in calibre has a well defined meaning, specified by ISO 639. The languages column will never accept arbitrary strings.