Relative Tempo Markings in Lilypond 2.22

[David M. Boothe, CAS]

I have a score in 2.18, one section of which uses with the following code:

\tempo \markup { \pad-to-box #'(0 . 0) #'(8 . 10)
              \concat {
                { \override #'(font-name . "Linux Biolinum Slanted")
\fontsize #1 "Musette  " }
              (
              \small \general-align #Y #DOWN \note #"8" #1
              " = "
              \small \general-align #Y #DOWN \note #"8" #1
              )
              }
          }
This produces the section title followed by eighth note equals eighth
note, in parentheses.

When I tried to render the score in 2.22, I received the following
error message:

/music_typeset/tonsing_pm+f/tonsing_pm+f3.ly:147:52: error: wrong type
for argument 1.  Expecting duration, found "8"
              \small \general-align #Y #DOWN \note
                                                   #"8" #1
As best I can tell, I'm using the form given in the manual, so I'm not
sure what this error means or how to fix it. Commenting out the code
to create the "Musette" title makes no difference.

I'm using Lilypond in Frescobaldi on WIndows 10.

Me: I've been using Lilypond for 15 or 16 years, but am new to this list.

Thanks for any help.

dB