Hello!
When I reply in some threads with some specific languages, such as Chinese and Japanese, there is a high possibility that "Body seems unclear, is it a complete sentence?" is shown and I can not reply.
I am sure I typed some complete sentences. Is there any solutions?
Thanks in advance.
It’s not just Chinese or Japanese, it happens with English and German as well.
My workaround is to add something, so the error won’t occur again. Mostly I just add a complaint about the problem along with 
to my comment. 
Wow, I added a smile face and I succeeded in sending my reply.
Thank you for your solution.
I hope someday I can send my message without such skills. 
It’s not the actual content of what is written that is checked, but rather if it looks like a regular sentence based on some basic heuristics (at least few words long, not a lot of repeated characters, not just punctuation marks, etc).
Unfortunately, this feature tends to trigger more often with Chinese/Japanese since it usually doesn’t need spaces which makes it look less like regular text to the code (albeit being perfectly valid). I have suggested a workaround for this to the Discourse team but I’m afraid they didn’t take it.