I've changed my mind. Considering what tomoe_musashi let us know in comment #7, this may simply be about how different available fonts, which handle Japanese, are prioritized. In that case it can be handled in a fontconfig .conf file.
I added a new fontconfig .conf file to language-selector-common, and uploaded the language-selector source package. This *might* fix this issue.
I've changed my mind. Considering what tomoe_musashi let us know in comment #7, this may simply be about how different available fonts, which handle Japanese, are prioritized. In that case it can be handled in a fontconfig .conf file.
I added a new fontconfig .conf file to language- selector- common, and uploaded the language-selector source package. This *might* fix this issue.