Applying tweaks to one voice in \partCombine

When using \partCombine, commands applying to a Voice context affect both parts since when are merged in the same Voice. This snippet defines a music function to apply tweaks to all elements of a certain kind in a music expression. This can be used to apply modifications to all grobs caused by elements of a music expression regardless of the context structure. Possible values for the event-class argument are listed at the Internals Reference

\version "2.26"

% LSR https://lists.gnu.org/archive/html/lilypond-user/2021-06/msg00242.html

tweakEverywhere =
#(define-music-function
   (parser location event-class property value music)
   (symbol? symbol-list-or-symbol? scheme? ly:music?)

   (for-some-music
    (lambda (m)
      (if (music-is-of-type? m event-class)
          (begin
            (set! (ly:music-property m 'tweaks)
                  (cons (cons
                         (if (symbol? property)
                             property
                             (apply cons* property))
                         value)
                        (ly:music-property m 'tweaks)))
            #t)
          #f))
    music)
   music)

soprano = { des' ees' fes' ges' fes' ges' aes' bes' }
tenor = { des' ees' fes' ges' des' ees' fes' ges' }

\partCombineUp \soprano
  \tweakEverywhere rhythmic-event font-size -3 \tenor
\partCombineUp \soprano
  \tweakEverywhere note-event Accidental.color #red \tenor