Why sqlite fts5 Unicode61 Tokenizer does not support CJK(Chinese Japanese Korean)?

Question

I had thought Unicode61 Tokenizer can support CJK -- Chinese Japanese Korean I verify my sqlite supports fts5

sqlite> pragma compile_options;
BUG_COMPATIBLE_20160819
COMPILER=clang-9.0.0
DEFAULT_CACHE_SIZE=2000
DEFAULT_CKPTFULLFSYNC
DEFAULT_JOURNAL_SIZE_LIMIT=32768
DEFAULT_PAGE_SIZE=4096
DEFAULT_SYNCHRONOUS=2
DEFAULT_WAL_SYNCHRONOUS=1
ENABLE_API_ARMOR
ENABLE_COLUMN_METADATA
ENABLE_DBSTAT_VTAB
ENABLE_FTS3
ENABLE_FTS3_PARENTHESIS
ENABLE_FTS3_TOKENIZER
ENABLE_FTS4
ENABLE_FTS5

But to my surprise it can't find any CJK word at all. Why is that ?

sqlite> CREATE VIRTUAL TABLE ft5_test USING fts5(content, tokenize = 'porter unicode61 remove_diacritics 1');
sqlite> INSERT INTO ft5_test values('为什么不支持中文 fts5 does not seem to work for chinese');
sqlite> select * from ft5_test where ft5_test = '中文';
sqlite>
sqlite> select * from ft5_test where ft5_test = 'Chinese';
为什么不支持中文 fts5 does not seem to work for chinese

------------- update ----------

I spend quite some time in building an icu version. I shared my experience here https://stackoverflow.com/a/52866566/301513

From what I have learned using icu version is the only way to support CJK and fts5 has not support icu tokenizer.

I leave my question here in case others may have new ideas about the problem.