Automatically run Action(s) when saving tags?

Is it possible to have Mp3tag automatically run Action(s) everytime you save tags? For example, I might add a value to the Composer field, and when I go to save the tag, I'd want mp3tag to automatically format the Artist field to take in %composer%.

The "actual" reason I'd like this though, is because I want to add Language tags to my mp3s, but since no music player I'm aware of supports the TLAN tag (foobar2000 and iTunes don't), I want to be able to run an action which looks at the 3-character code, runs it through if statements to turn eng->English, kor->Korean, etc., then writes the new word in a custom tag, so at least foobar2000 can read it.

Thus, I'd save 2 tags everytime I add one tag.