The command which controls the clef is K:
which also sets the key (it is unclear to me whether you need to specify the key here, but by using 'C' at least no extra accidentals will be printed).
And apparently (some) commands can be inserted by enclosing in [ ]
.
So the following appears to work, using embedded [K:]
commands.
X:1
L:1/8
M:4/4
K:C
%%score V1 V2 VA CL
V:V1 clef=treble name="Vn.I"
V:V2 clef=treble name="Vn.II"
V:VA clef=alto name="Viola"
V:CL clef=bass name="Cello"
% 1
[V:V1] "P0""_0"=D4 "_1"^C4 | "_2"=A,A,A,"_3"_B, "_4"=F2 "_5"_E2 | "_6"=EEE"_7"=c "_8"_B4 | ("_9"=G4G)"_10"^FF"_11"=B |(=B8 | B3) z "I5"z4 | "_0"=gz/2g/2 g z z2 "_1"_a z | "_4"=e z z2 z2 "_6"=fz/2f/2 | f z z2 z4 |
[V:V2] z2 "_3"_B, z "_8"_A, z "_10"^F z | z2 "_6"=E z "_11"=B, z "_1"^C z | z2 "_9"=G z "_0"=D z "_5"_E z | z4 "_1"^C2 C2 |^C2 "_5"^D2 (D4 | D) z "_6"=E z z "_0"=G"_1"_A"_2"=c | ("_3"=B4 B)("_4"=e"_5"^F2) | z "_6"=F"_7"=A"_8"^c ("_9"=D"_10"_e') (e'2 | (e'2) "_11"_B6) |
[V:VA] z2 "_5"^D, z "_6"=E, z "_9"=G, z | z2 "_7"=C, z "_10"^F, z "_2"=A, z | z2 "_11"=B, z "_2"=A, z "_4"=F, z | z4 "_0"=D,2 D,2 |=D,2 "_4"=F,2 (F,4 | F,) z "_8"_A, z z4 | "_2"=C,z/2C,/2 C, z z2 =c z | "_3"=B z z2 z2 "_8"^C,z/2C,/2 | C, z z2 "_9"=Cz/2C/2 C z |
[V:CL] z2 "_4"=F,, z "_7"=C, z "_11"=B,, z |\
z2 "_8"_A,, z "_9"=G,, z "_0"=D,, z |\
z2 "_10"^F, z "_1"^C, z "_3"_B,, z |\
z4 "_2"=A,,2 A,,2 |\
=A,,2 "_3"_B,,2 (B,,4 |\
B,,) z "_7"=C, z z4 |\
[K:C alto] "_1"_Az/2A/2 A z z2 "_0"=G, z |\
"_5"^F z z2 z2 "_7"=Az/2A/2 |\
A [K:C bass] z z2 "_10"_E,,z/2E,,/2 E,, z |
X:1
L:1/8
M:4/4
K:C
%%score V1 V2 VA CL
V:V1 clef=treble name="Vn.I"
V:V2 clef=treble name="Vn.II"
V:VA clef=alto name="Viola"
V:CL clef=bass name="Cello"
% 1
[V:V1] "P0""_0"=D4 "_1"^C4 | "_2"=A,A,A,"_3"_B, "_4"=F2 "_5"_E2 | "_6"=EEE"_7"=c "_8"_B4 | ("_9"=G4G)"_10"^FF"_11"=B |(=B8 | B3) z "I5"z4 | "_0"=gz/2g/2 g z z2 "_1"_a z | "_4"=e z z2 z2 "_6"=fz/2f/2 | f z z2 z4 |
[V:V2] z2 "_3"_B, z "_8"_A, z "_10"^F z | z2 "_6"=E z "_11"=B, z "_1"^C z | z2 "_9"=G z "_0"=D z "_5"_E z | z4 "_1"^C2 C2 |^C2 "_5"^D2 (D4 | D) z "_6"=E z z "_0"=G"_1"_A"_2"=c | ("_3"=B4 B)("_4"=e"_5"^F2) | z "_6"=F"_7"=A"_8"^c ("_9"=D"_10"_e') (e'2 | (e'2) "_11"_B6) |
[V:VA] z2 "_5"^D, z "_6"=E, z "_9"=G, z | z2 "_7"=C, z "_10"^F, z "_2"=A, z | z2 "_11"=B, z "_2"=A, z "_4"=F, z | z4 "_0"=D,2 D,2 |=D,2 "_4"=F,2 (F,4 | F,) z "_8"_A, z z4 | "_2"=C,z/2C,/2 C, z z2 =c z | "_3"=B z z2 z2 "_8"^C,z/2C,/2 | C, z z2 "_9"=Cz/2C/2 C z |
[V:CL] z2 "_4"=F,, z "_7"=C, z "_11"=B,, z |\
z2 "_8"_A,, z "_9"=G,, z "_0"=D,, z |\
z2 "_10"^F, z "_1"^C, z "_3"_B,, z |\
z4 "_2"=A,,2 A,,2 |\
=A,,2 "_3"_B,,2 (B,,4 |\
B,,) z "_7"=C, z z4 |\
[K:C alto] "_1"_Az/2A/2 A z z2 "_0"=G, z |\
"_5"^F z z2 z2 "_7"=Az/2A/2 |\
A [K:C bass] z z2 "_10"_E,,z/2E,,/2 E,, z |