Comment 14 for bug 1173571

After my testing, the good news is that insatalling fonts-droid will provide better visual appearence and more readible than WQY zen-hei in Chinese charaters.

However, 69-language-selector-zh-tw.conf has a weird UNACCEPTABLE side effect. It matches DejaVu Serif for "sans-serif" and "monospace" first.

The result of 'fc-match -s serif' returns
uming.ttc: "AR PL UMing TW" "Light"
DejaVuSerif.ttf: "DejaVu Serif" "Book"
DejaVuSerif-Bold.ttf: "DejaVu Serif" "Bold"
DejaVuSans.ttf: "DejaVu Sans" "Book"
DejaVuSans-Bold.ttf: "DejaVu Sans" "Bold"
uming.ttc: "AR PL UMing HK" "Light"
Kinnari.ttf: "Kinnari" "Medium"
wqy-zenhei.ttc: "文泉驛正黑" "Regular"
[...]
We can see that AR PL UMing TW is the first font for serif. It is not that good because we would like to see DejaVu Serif to present Western text more than AP PL UMing. The Western text gylphs come from AR PL UMing are not as good as those gylphs Western fonts provide. However, the result is acceptable.

The result of 'fc-match -s sans-serif' returns
DejaVuSerif.ttf: "DejaVu Serif" "Book"
DejaVuSerif-Bold.ttf: "DejaVu Serif" "Bold"
DejaVuSans.ttf: "DejaVu Sans" "Book"
DejaVuSans-Bold.ttf: "DejaVu Sans" "Bold"
DroidSansFallbackFull.ttf: "Droid Sans Fallback" "Regular"
wqy-zenhei.ttc: "文泉驛正黑" "Regular"
uming.ttc: "AR PL UMing TW" "Light"
uming.ttc: "AR PL UMing HK" "Light"
[...]
This is completly unacceptable because DejaVu Serif and DejaVu Serif Bold are not sans-serif style font.

The result of 'fc-match -s monospace' returns
DejaVuSerif.ttf: "DejaVu Serif" "Book"
DejaVuSerif-Bold.ttf: "DejaVu Serif" "Bold"
DejaVuSansMono.ttf: "DejaVu Sans Mono" "Book"
DejaVuSansMono-Bold.ttf: "DejaVu Sans Mono" "Bold"
DroidSansFallbackFull.ttf: "Droid Sans Fallback" "Regular"
wqy-zenhei.ttc: "文泉驛等寬正黑" "Regular"
uming.ttc: "AR PL UMing TW" "Light"
uming.ttc: "AR PL UMing HK" "Light"
n022003l.pfb: "Nimbus Mono L" "Regular"
[...]
This is completly unacceptable because DejaVu Serif and DejaVu Serif Bold are not monospace style font.

After rm 69-language-selector-zh-tw.conf,

The result of 'fc-match -s serif' returns
uming.ttc: "AR PL UMing TW" "Light"
DejaVuSerif.ttf: "DejaVu Serif" "Book"
DejaVuSerif-Bold.ttf: "DejaVu Serif" "Bold"
DejaVuSans.ttf: "DejaVu Sans" "Book"
DejaVuSans-Bold.ttf: "DejaVu Sans" "Bold"
uming.ttc: "AR PL UMing HK" "Light"
Kinnari.ttf: "Kinnari" "Medium"
wqy-zenhei.ttc: "文泉驛正黑" "Regular"
[...]
The reslt is the same with haveing 69-language-selector-zh-tw.conf, so it implies that 69-lanaguage-selctor-zh-tw.conf does not paly a big role in this "serif" case.

The result of 'fc-match -s sans-serif' returns
DejaVuSans.ttf: "DejaVu Sans" "Book"
DejaVuSans-Bold.ttf: "DejaVu Sans" "Bold"
wqy-zenhei.ttc: "文泉驛正黑" "Regular"
n019003l.pfb: "Nimbus Sans L" "Regular"
Waree.ttf: "Waree" "Book"
ukai.ttc: "AR PL UKai CN" "Book"
ukai.ttc: "AR PL UKai HK" "Book"
uming.ttc: "AR PL UMing CN" "Light"
[...]
DejaVu Sans is sans-serif style font. The result is acceptable.

The result of 'fc-match -s monospace' returns
DejaVuSansMono.ttf: "DejaVu Sans Mono" "Book"
DejaVuSansMono-Bold.ttf: "DejaVu Sans Mono" "Bold"
wqy-zenhei.ttc: "文泉驛等寬正黑" "Regular"
n022003l.pfb: "Nimbus Mono L" "Regular"
[...]
DejaVu Sans Mono is monospace style font. The result is acceptable.

It seems that fontconfig will prepend a full font family of DejaVu Serif for 69-language-selector-zh-tw.conf. Thus I check this configuration in detail.

I find that we prepend AR PL UMing TW as first font for serif. And in last section of this configuraton, we define that DejaVu Serif should bind to AR PL UMing TW. This section is also outdated too. The original idea behind this is to mimic the old ubuntu default font setting, but things have changed. I guess this might be the cause and give a test.

If we remove the last section which binds DejaVu Serif with AR PL UMing,

The result of 'fc-match -s serif' returns
uming.ttc: "AR PL UMing TW" "Light"
DejaVuSerif.ttf: "DejaVu Serif" "Book"
DejaVuSerif-Bold.ttf: "DejaVu Serif" "Bold"
DejaVuSans.ttf: "DejaVu Sans" "Book"
DejaVuSans-Bold.ttf: "DejaVu Sans" "Bold"
uming.ttc: "AR PL UMing HK" "Light"
Kinnari.ttf: "Kinnari" "Medium"
wqy-zenhei.ttc: "文泉驛正黑" "Regular"
[...]
Well, still the same. 69-language-selector-zh-tw.conf seems to have no big effect for serif.

The result of 'fc-match -s sans-serif' returns
DejaVuSans.ttf: "DejaVu Sans" "Book"
DejaVuSans-Bold.ttf: "DejaVu Sans" "Bold"
DroidSansFallbackFull.ttf: "Droid Sans Fallback" "Regular"
wqy-zenhei.ttc: "文泉驛正黑" "Regular"
uming.ttc: "AR PL UMing TW" "Light"
uming.ttc: "AR PL UMing HK" "Light"
[...]
Good! DejaVu Serif and DejaVu Serif Bold are not prepended here. The result is acceptable.

The result of 'fc-match -s monospace' returns
DejaVuSansMono.ttf: "DejaVu Sans Mono" "Book"
DejaVuSansMono-Bold.ttf: "DejaVu Sans Mono" "Bold"
DroidSansFallbackFull.ttf: "Droid Sans Fallback" "Regular"
wqy-zenhei.ttc: "文泉驛等寬正黑" "Regular"
uming.ttc: "AR PL UMing TW" "Light"
uming.ttc: "AR PL UMing HK" "Light"
n022003l.pfb: "Nimbus Mono L" "Regular
[...]
Good! DejaVu Serif and DejaVu Serif Bold are not prepended here. The result is acceptable.

So, my suggestion to get a better visual reslut for Chinese (Traditional) users is that
0. make font-droid as the dependent package for zh-tw language support as Gunnar Hjalmarsson said.
1. remove the outdated binding things listed at the last part of 65-ttf-wqy-microhei.conf.
2. remove the outdated binding things listed at the last part of 69-language-selector-zh-tw.conf.