problem overriding fonts

[Noeck]

Hi,

I want to use a different font in general (titles, lyrics, etc.) but keep
Century Schoolbook L for some parts like MetronomeMarks and BarNumbers.
How can I do that without loosing the ability to choose the font weight/shape in
the markup using \bold, \italic or \medium?

\version "2.18.2"

\paper {
  fonts = #
  (make-pango-font-tree
   "Linux Libertine O"
   "Linux Biolinum O"
   "Ubuntu Mono"
   (/ (* staff-height pt) 2.5))
}

{
  \tempo \markup { Andante \italic con \bold moto \medium etc } a1^"good as
before with Century S. but I want a different font" \break
  \override Score.MetronomeMark.font-name = #"Century Schoolbook L"
  \tempo \markup { Andante \italic con \bold moto \medium etc } a1^"bad: not
bold by default, ignores bold and italic" \break
  \override Score.MetronomeMark.font-name = #"Century Schoolbook L bold"
  \tempo \markup { Andante \italic con \bold moto \medium etc } a1^"bad: ignores
medium and italic"
}

Joram