I think the issue might be that I am using explicit \coda and \segno commands and your example uses the new \repeat segno form which will be too complex in the specific big band chart I'm editing. It's about 160 bars long with the segno in bar 24 and the "to coda" symbol in bar 48 and three repeated sections, I got lost in the nested braces when I tried the new structure. If I was writing it from scratch rather than re-editing it would be simpler.
That is indeed the issue, as those marks are a different type. Just needs a different override in a different context. Turns out that using the \coda and \segno commands the symbols created are handled the same as articulations. That means they fall into the somewhat more generic Script type, which is handled in the Voice context. Therefor:
\layout {
\context {
\Score
\override CodaMark.color = #red
\override SegnoMark.color = #red
\override SectionLabel.color = #red
\override SectionLabel.font-size = #3
\override RehearsalMark.font-size = #3
\override RehearsalMark.color = #red
\override TextMark.color = #red
}
\context {
\Voice
\override Script.color = #red
}
}
should get you sorted.
Michael