Steps to reproduce:
1) Go to Options > Other > change locale to Chinese (zh-CN) or Chinese Traditional (zh-TW, 90%)
2) Restart Factorio.
3. Go to Options > Other again. See the language names.
Compared with Some of the special characters are completely missing (Č, š, ñ, ç), while ê has large spacing.
I saw this report: [0.14.17]Russian characters is not displayed, which was marked as Won't Fix.
But since the language selection UI is a built-in feature, I guess this is different? It will be your decision.
![Wink ;)](./images/smilies/icon_e_wink.gif)