[itsme]

@Mike:
> Please also note that I have upcoming changes to the chord localization processing so the behavior of the current version probably shouldn't be the basis of the conversation. 
> Instead, we need to discuss how it should behave in general.
That's why I bring this up as long as chord localization is still work in progress

> If I encounter a "B" in a file with localization set to Deutsch, for example, how do I know if that is an actual "B" or a "Bb"?  
You cannot "know" that, it is ambiguous. It needs a setting so that the user can specify it or you have to define a rule what is expected by MSP.
Re-using the "show" setting is the worst solution. That would require on ANY change of the localization setting that I need to search through ALL my chordpro files if they contain an affected chord. Otherwise transposing produces confusingly wrong results as in my "Fields Of Athenry" example.

It's really worth taking a look at Sciurius' reference implementation, he has implemented it already with (hopefully) all bells and whistles.