Currently the only option available in the "belongs on another site in the Stack Exchange network" menu is chinese.meta.stackexchange.com.
That's definitely not exhaustive. Other items in that menu that would make sense are:
- japanese.stackexchange.com: rather easy for newbies to confuse Japanese with Chinese.
- linguistics.stackexchange.com: even though we have a [linguistics] tag, its purpose is basically to restrict the scope of terminology questions, or for questions about Chinese but with highly technical content.
- anything else?
That aside, following this thread Can we have a “Not about the Chinese language” close reason? a clarification is needed.
If the "not about Chinese" close reason is approved, when would you choose that over "belongs to another site in SE"?
In short, the answer to that is: you choose "Not about Chinese" over "belongs to another site" when the question would be off-topic on that other site, i.e. no migration would be possible. Remember that marking a question as "belongs to another site" in practice means "mods should migrate this question over there". If the question would be off-topic over there, then it doesn't actually belong there, and "Not about Chinese", or another applicable close reason, should be chosen instead. Or when the site it would be on-topic on isn't in the list.