I have found that adding language codes begin with "zh-" such as "zh-tw", "zh-cn", "zh-hk" to babel in user page has no effect in Wikidata, except "zh-hant" and "zh-hans".
Let me describe how I reproduce this bug.
First, I choose the English user interface, but it seems that Wikidata automatically shows some other languages for me (I'm not sure if it is because of I'm in Taiwan or I have once edited in these languages before).
With an empty user page, an entity looks like this:
Then I add some language codes
After saving the user page, an entity looks like this:
The expected result is that all language codes added to babel should appear when we view an entity.
We can see that "en", "zh", "ja", "zh-hant" and "zh-hans" works fine, but "zh-tw" disappeared and "zh-cn" has no effect.
They used to be working fine for me till August 18th, 2018, but the bug emerged when I edited my user page on December 12th, 2018.
my environments:
- Browser: Google Chrome 71.0.3578.98
- OS: Windows10
- Location: Taiwan
- Preference > User profile > Internationalisation > Language : en - English
- Preference > Editing > Translation options > Assistant languages : default