Hola, manejo la versión 2.10.33
He modificado espanol.ly con cuartos de tono y x para los dobles
sostenidos.
Así dotcb (do_tres_cuartos_bemol) es do -3/4 de tono, docb es do -1/4,
docs es do +1/4, dotcs es do + 3/4 de tono y dox do doble sostenido.

Aquí os pongo el contenido de espanol.ly por si alguien lo desea
utilizar (Hay que crear un archivo espanol.ly, copiar este contenido y
sustituirlo por el archivo que tiene el mismo nombre dentro de vuestro
directorio de lilypond - en mi caso /usr/share/lilypond/2.10.33/ly ).
Creo que está correcto, por la pruebas que he hecho, pero
como soy nuevo en lilypond puede que meta la pata en algo que
desconozco. (Es recomendable hacer una copia de seguiridad del
anterior espanol.ly)

%{

Common Spanish names for notes. "b" means flat (bemol), "s" means
sharp (sostenido).
Adapted from italiano.ly.

English: a b c d e f g
Spanish: la si do re mi fa sol

%}

% contributed by Carlos García Suárez <<cgscqmp@...>>

% For using "sostingut" notation, which is also correct

% cuartos de tono y "x" para doble sostenido <<mxgdvg@...>>

pitchnamesEspanol = #`(
(dobb . ,(ly:make-pitch -1 0 DOUBLE-FLAT))
(dob . ,(ly:make-pitch -1 0 FLAT))
(do . ,(ly:make-pitch -1 0 NATURAL))
(dos . ,(ly:make-pitch -1 0 SHARP))
(doss . ,(ly:make-pitch -1 0 DOUBLE-SHARP))

(rebb . ,(ly:make-pitch -1 1 DOUBLE-FLAT))
(reb . ,(ly:make-pitch -1 1 FLAT))
(re . ,(ly:make-pitch -1 1 NATURAL))
(res . ,(ly:make-pitch -1 1 SHARP))
(ress . ,(ly:make-pitch -1 1 DOUBLE-SHARP))

(mibb . ,(ly:make-pitch -1 2 DOUBLE-FLAT))
(mib . ,(ly:make-pitch -1 2 FLAT))
(mi . ,(ly:make-pitch -1 2 NATURAL))
(mis . ,(ly:make-pitch -1 2 SHARP))
(miss . ,(ly:make-pitch -1 2 DOUBLE-SHARP))

(fabb . ,(ly:make-pitch -1 3 DOUBLE-FLAT))
(fab . ,(ly:make-pitch -1 3 FLAT))
(fa . ,(ly:make-pitch -1 3 NATURAL))
(fas . ,(ly:make-pitch -1 3 SHARP))
(fass . ,(ly:make-pitch -1 3 DOUBLE-SHARP))

(solbb . ,(ly:make-pitch -1 4 DOUBLE-FLAT))
(solb . ,(ly:make-pitch -1 4 FLAT))
(sol . ,(ly:make-pitch -1 4 NATURAL))
(sols . ,(ly:make-pitch -1 4 SHARP))
(solss . ,(ly:make-pitch -1 4 DOUBLE-SHARP))

(labb . ,(ly:make-pitch -1 5 DOUBLE-FLAT))
(lab . ,(ly:make-pitch -1 5 FLAT))
(la . ,(ly:make-pitch -1 5 NATURAL))
(las . ,(ly:make-pitch -1 5 SHARP))
(lass . ,(ly:make-pitch -1 5 DOUBLE-SHARP))

(sibb . ,(ly:make-pitch -1 6 DOUBLE-FLAT))
(sib . ,(ly:make-pitch -1 6 FLAT))
(si . ,(ly:make-pitch -1 6 NATURAL))
(sis . ,(ly:make-pitch -1 6 SHARP))
(siss . ,(ly:make-pitch -1 6 DOUBLE-SHARP))



(dotcb . ,(ly:make-pitch -1 0 THREE-Q-FLAT))
(docb . ,(ly:make-pitch -1 0 SEMI-FLAT))
(docs . ,(ly:make-pitch -1 0 SEMI-SHARP))
(dotcs . ,(ly:make-pitch -1 0 THREE-Q-SHARP))
(dox . ,(ly:make-pitch -1 0 DOUBLE-SHARP))

(retcb . ,(ly:make-pitch -1 1 THREE-Q-FLAT))
(recb . ,(ly:make-pitch -1 1 SEMI-FLAT))
(recs . ,(ly:make-pitch -1 1 SEMI-SHARP))
(retcs . ,(ly:make-pitch -1 1 THREE-Q-SHARP))
(rex . ,(ly:make-pitch -1 1 DOUBLE-SHARP))

(mitcb . ,(ly:make-pitch -1 2 THREE-Q-FLAT))
(micb . ,(ly:make-pitch -1 2 SEMI-FLAT))
(mics . ,(ly:make-pitch -1 2 SEMI-SHARP))
(mitcs . ,(ly:make-pitch -1 2 THREE-Q-SHARP))
(mix . ,(ly:make-pitch -1 2 DOUBLE-SHARP))

(fatcb . ,(ly:make-pitch -1 3 THREE-Q-FLAT))
(facb . ,(ly:make-pitch -1 3 SEMI-FLAT))
(facs . ,(ly:make-pitch -1 3 SEMI-SHARP))
(fatcs . ,(ly:make-pitch -1 3 THREE-Q-SHARP))
(fax . ,(ly:make-pitch -1 3 DOUBLE-SHARP))

(soltcb . ,(ly:make-pitch -1 4 THREE-Q-FLAT))
(solcb . ,(ly:make-pitch -1 4 SEMI-FLAT))
(solcs . ,(ly:make-pitch -1 4 SEMI-SHARP))
(soltcs . ,(ly:make-pitch -1 4 THREE-Q-SHARP))
(solx . ,(ly:make-pitch -1 4 DOUBLE-SHARP))

(latcb . ,(ly:make-pitch -1 5 THREE-Q-FLAT))
(lacb . ,(ly:make-pitch -1 5 SEMI-FLAT))
(lacs . ,(ly:make-pitch -1 5 SEMI-SHARP))
(latcs . ,(ly:make-pitch -1 5 THREE-Q-SHARP))
(lax . ,(ly:make-pitch -1 5 DOUBLE-SHARP))

(sitcb . ,(ly:make-pitch -1 6 THREE-Q-FLAT))
(sicb . ,(ly:make-pitch -1 6 SEMI-FLAT))
(sics . ,(ly:make-pitch -1 6 SEMI-SHARP))
(sitcs . ,(ly:make-pitch -1 6 THREE-Q-SHARP))
(six . ,(ly:make-pitch -1 6 DOUBLE-SHARP))

)

pitchnames = \pitchnamesEspanol

\version "2.10.0"

#(ly:parser-set-note-names parser pitchnames)