This missing fallback is very unfortunate.
Benjamin Chen, 17/11/2012 15:02:
For things like centralNotices and fundraising
banners, the software doesn't support automatic fallback or variant conversion (yet).
So we usually translate a simplified version and a traditional version, then
copy&paste then into all the variants. Otherwise users with their interface set to
things like zh-cn or zh-tw will get their messages in English.
Note that with the Translate extension you can define one or all Chinese
variants as "assistant languages" so that instead of copy and pasting
you can just see the relevant translations and copy them with a click.