My system had a similar problem: I was able to choose "Chinese", but it didn't really input any Chinese. The key step missing was to install a specific Chinese input method/package. E.g.:

sudo apt-get install ibus-pinyin 

After installing Pinyin in this example, go to System Settings → Language Support → Chinese (Pinyin).

Now it works as expected.

This thread helped me to figure out this solution. It also suggests another input method:

sudo apt-get install ibus-sunpinyin

P.S.

After either of those commands do not forget to restart the IBus daemon

ibus restart

1. click dash home, search for "language support"

2. click "install/remove language" and add Chinese

3. click dash home, search for "keyboard input method"

4. under "input method",add Chinese input method

5. enjoy!

hopefully it helps

setup instructions for chinese character support in (ubuntu 14.04) and (ubuntu 16.04)

1. Enable Chinese Language Support

a - Click System Settings, Click Language Support

you may be prompted to install support for current languages

b - Ensure that Keyboard input method system: is set to IBus

c - Click Install / Remove Languages..

d - Choose Chinese (simplified) and/or Chinese (traditional)

e - (ubuntu 14.04) - Click Apply Changes

e - (ubuntu 16.04, 18.04, 20.04) - Click Apply

Logout Login<

2. Install Additional Chinese Input Systems

this step will not work for 16.04 as ibus-m17n can no longer be found through software center

a - Open Ubuntu Software Center

b - Search for and install ibus-m17n

Logout Login<

3. Select And Enable Your Input Systems

a - Click System Settings, Click Text Entry

b - Click the + button to add new methods

c - Select Chinese (Pinyin), click Add

this allows you to type characters 汉字

the following steps will not work for 16.04 because they depend on ibus-m17n being installed (i'll update another time when i get them installed myself. here's a decent starting point

d - Select Chinese (SunPinyin), click Add

this also allows you to type chinese characters 汉字 (optional alternative)

e - select Chinese (hanyu pinyin (m17n)), click Add

this allows you to type hànyǔ pīnyīn (english characters with tone markers)

Logout Login<

4. Test It Out

Troubleshooting

If when using Chinese(Pinyin) you have the bug where typing hanyu suggests ha nü sh and other similar, syllabic separation problems, first try this..

Open the terminal, Enter ibus restart

if that doesn't work here are a few other suggestions at Pinyin Joe