Function for rendering key textually in 3 languages

[Olivier Biot]

Hi all,

I'd like to have a function to translate a key signature into the
textual representation of that key in 3 languages.

For instance, I'd write this in my score:
<raw>
header {
  piece-key = "c#"
}
</raw>

and the rendering would look like this:
<raw>
\markup {"Cis moll." \italic { "Do dièse mineur." } "C sharp minor."}
</raw>

The logic I'm trying to implement, is (in pseudo-code):
1. key format = <key_name> [<accidentals>]
2. IF <key_name> is lowercase THEN key is minor ELSE key is major.
3. If accidentals are added, they pertain to the key name

How should I proceed?

Best regards,

Olivier