A user, schungx, has encountered an issue where all-capitalized English words in topic titles are converted to lowercase, except for the first letter, when the title includes non-English characters (e.g., CJK). This issue does not occur in English-only titles.
schungx discovered a similar issue reported on meta.discourse.org and found that disabling “title prettify” resolves the issue but causes problems with CJK titles containing all-caps English words, as the system then rejects them.
schungx further researched and found that the titles were being flagged by a rule checking for unclear titles, which can be disabled. The user suggests that titles with a majority of non-English letters should bypass English-based rules, as the English letters are likely markers, IDs, model names, or symbols.
I’ve hit on a strange problem.
The titles of topics, if they include non-English characters (e.g. CJK), all-capitalized English words get turned into lower-case, except for the first letter which is upper-case.
This does not happen in English titles.
For example:
PPT: This is a POWERPOINT presentation
is not affected, but:
PPT: 這是POWERPOINT報表
gets turned into
Ppt: 這是powerpoint報表
It does not seem to affect words that are mix-casing.
OK, found this:
So, I tried turning off tittle prettify, but then it rejects all my CJK titles with all-caps English words. If I change those all-caps English words into mix-caps, then it is accepted.
The rejection says: Title seems unclear, is it a complete sentence?
If I change even one letter in the all-caps word into lower-case, then suddenly it seems to be a complete sentence to the system. 
SUGGESTION: When a title contains more non-English letters than English letters, it is most likely a foreign language. In that case, you really should be by-passing most of the English-based rules.
No worries. Found this:
Turns out that the titles I entered have CJK characters, symbols and all-caps words. Thus trapped under this rule.
Again, for titles with a majority of non-English letters, this really should be turned off, because those English letters are probably markers, ID’s, model names, and other symbols.