Changing how a font style is requested

[Alexander Kobel]

Dear all,

I like to use the Romande ADF font family [1] in one of my scores. I do 
the usual rule-of-three with

  \paper { ... (make-pango-font-tree
                "Romande ADF No2 Std" "Romande ADF Std" "monospace"
                (/ myStaffSize 20)) ... }

(If you wonder, No2 is condensed, and the non-condensed version, used in 
the headers, is mapped to sans for easy access.)

However, here's the catch: Romande does offer a bold variant, but it 
announces it as "DemiBold" instead of "Bold", according to fc-list. I 
know that I can switch to the different font each time I need bold, but 
that's an utter nuisance.
Is there any way to tell Lily how to choose a bold variant? Bonus points 
if it only applies to a specific, say, the serif font. Or, <wishlist to 
follow>, if it is possible to define a mapping similar to

  myserif = { regular:     # default
                           "Romande ADF No2 Std:style=Regular",
              bold:        # choose way of selecting bold
                           "Romande ADF No2 Std:style=DemiBold",
              italic:      # pretend I don't like Romande's italics
                           # and need to scale some other font to match
                           "Gentium:style=Italic:scaling=0.93",
              bold-italic: # use small caps family instead
                           "Romande ADF Style Std:style=Regular" }
  ...
  \paper { #(define fonts (myserif mysans mymono (/ myStaffSize 20)) }

Obviously, that's not Lily's syntax, but you get the point...


Thanks in advance,
Alexander


[1] http://arkandis.tuxfamily.org/adffonts.html