How to do TextSpanner + markup + override vertical placement all at the same time?

[Kenneth Wolcott]

Hi;

  I know how to generate a bold and large "rall." and "a tempo".

  I know how to get a text span.

  How to merge these two concepts?

  Also I need to put the "a tempo" above the ottava.

  I think I now how to do that in a more simple context, but I'm
struggling here.

  I have attached two screenshots.

  The example is the music I'm trying to engrave from while the other
screenshot is what I've asked Lilypond to do,

I have enclosed below an excerpt of my Lilypond code.

Thanks in advance for your help.

Ken Wolcott

%%%%%%%%%%%%%%%%
\version "2.22.0"
...
  \language "english"
...
a_tempo = ^\markup { \bold "A tempo" }
rall = ^\markup { \bold "rall." }
rit = ^\markup { \bold "rit." }
...
%\break
  bf'4. \( g'8 af' g' f' ef'                             | % m18
  \override TextSpanner.bound-details.left.text = "rall."
  g'4 bf8 c'\startTextSpan ef'2 \)                       | % m19
  f'8 \( g' ef''8. c''16 bf'8.\fermata c''16 ef'8. f'16  | % m20
  g'4 g'8 f' ef'2\stopTextSpan \)                        | % m21
%\break
  \ottava 1
    \transpose c c' {
    \override TextSpanner.bound-details.left.text = "a tempo"
    \grace { af'16\startTextSpan } g'8 \( f' g' bf' bf' g'' g''4 \)  | % m22
    c''8 \( af'' ef'' f'' g''4\stopTextSpan \) r                     | % m23
  }
  \ottava 0
  f''8\rall \( g'' ef''' c''' bf'' c'' ef'' f''                    | % m24
  g''4 g''8 f'' <g' ef''>4 \) s                                    | % m25
  \bar "|."
%%%%%%%%%%%%%%%%%%%%

example.png
Description: PNG image

my_engraving.png
Description: PNG image