This is now completed per:
https://github.com/discourse/discourse/commit/f74a6457ee9a3ef4cb9f0d4283a8604e5b05551e
We will have it deployed on the business tier next week. The site setting search_tokenize_chinese_japanese_korean will enable the CJK tokenizer for search regardless of locale.
To take effect you will have to enable the site setting and edit the topic in question (to refresh the search index)