Even though /etc/sysconfig/fonts-config have the following line generated by
YaST font module, /usr/sbin/fonts-config does not generate family preference
list into 58-family-prefer-local.conf.

PREFER_SANS_FAMILIES=Noto Sans CJK JP,Noto Sans CJK JP DemiLight


It seems that since $OPT_SERIF_FAMILIES is 0, configs from
/etc/sysconfig/fonts-config are not loaded correctly.

Here is the log of fonts-config:

$ sudo /usr/sbin/fonts-config -d -v   
SYSTEM mode
--- sysconfig options (read from /etc/sysconfig/fonts-config):
GENERATE_TTCAP_ENTRIES=yes
FORCE_BW_MONOSPACE=no
USE_LCDFILTER=lcdnone
USE_RGBA=none
FORCE_FAMILY_PREFERENCE_LISTS=no
GENERATE_JAVA_FONT_SETUP=yes
PREFER_SANS_FAMILIES=Noto Sans CJK JP,Noto Sans CJK JP DemiLight
FORCE_HINTSTYLE=none
PREFER_SERIF_FAMILIES=IPA P������,IPAPMincho
PREFER_MONO_FAMILIES=
SEARCH_METRIC_COMPATIBLE=yes
FORCE_BW=no
USE_EMBEDDED_BITMAPS=yes
VERBOSITY=256
EMBEDDED_BITMAPS_LANGUAGES=ja:ko:zh
FORCE_AUTOHINT=no
---
--- font directories
(snipped)
--- generating  /etc/fonts/conf.d/58-family-prefer-local.conf ---
--- writing /etc/fonts/conf.d/30-metric-aliases.conf ---
---
--- writing /etc/fonts/conf.d/58-family-prefer-local.conf ---
---
--- Creating cache files for fontconfig --- executing: /usr/bin/fc-cache
--verbose 
(snipped)