Split from T289554: Japanese font no longer works in Score addlyrics.

In T289554#7305513, @Bcxfu75k wrote:

Legoktm, your screen shot looks serif font but 'Noto Sans CJK' would be the best. Because jawiki uses Sans-serif fonts for all pages.
(I guess it would be called 'fonts-noto-sans-cjk'. )
Reedy's screen shot is Sans fonts, which I preferred.

In T289554#7305957, @Legoktm wrote:

I'm relatively confident that LilyPond is what's forcing the use of a serif font, English text uses serif too (though I couldn't find exactly where in the code it was doing that). When I asked Reedy about his system, he only had a sans-serif Japanese font installed, so it had to use that even if it wanted a serif.

So I propose that right now we deploy using of fonts-noto-cjk, so you at least have *some* fonts in the short term even though it uses serif. Theoretically you can use \markup { \sans "...." } but I couldn't get that to align properly with \addlyrics, possibly I'm missing something (see LP docs).

Then we can look into having sans-serif be default by:

• Forcing LilyPond to use sans-serif font for Japanese lyrics
• Telling fontconfig to use sans-serif font even if serif was asked for (this would prevent using any serif fonts at all though).
• Removing the serif fonts from the container (this would affect all other CJK languages too)

All of which are more complicated, so I don't want to do it immediately.