Bar numbers and multiple tempo lines

[Kevin Pye]

I often generate vocal scores with multiple staves in a ChoirStaff and two staves in a PianoStaff. Typically such scores have the tempo markings both above the ChoirStaff and above the PianoStaff.

This is easily done in Lilypond by moving the Metronome_mark_engraver and Staff_collecting_engraver from the Score context to the ChoirStaff and PianoStaff contexts, as in this example:

\version "2.25.0"

\header {
  title       = "title"
}

tempoTrack = {
  \tempo Moderato 4=120
}

music = \relative {
  c'4 c c c c c c c c c c c c c c c c

  c c c c c c c c c c c c c c c c c c c c c
  c c c c c c c c c c c c c c c c c c
  \bar "|."
}

\book {
  \score {
    <<
      \new ChoirStaff <<
        \new Staff
        <<
          \new Voice \TempoTrack
          \new Voice \music
        >>
        \new Staff
        <<
          \new Voice \music
        >>
      >>
      \new PianoStaff <<
        \new Staff
        <<
          \new Voice \TempoTrack
          \new Voice \music
        >>
      >>
    >>
    \layout {
      \context {
        \Score
        \remove Metronome_mark_engraver
        \remove Staff_collecting_engraver
      }
      \context {
        \ChoirStaff
        \consists Metronome_mark_engraver
        \consists Staff_collecting_engraver
      }
      \context {
        \PianoStaff
        \consists Metronome_mark_engraver
        \consists Staff_collecting_engraver
      }
    }
  }
}

However, when this is done the bar numbers are lowered, and conflict with the ChoirStaff bracket:

(Normally the bar numbers would be higher so as not to collide with the bracket.)  Presumably this is because the Bar_number_engraver also uses the results of the Staff_collecting_engraver.

Is there an easy fix?

Kevin.