Some search keys with 3 Chinese return NO result

Issue Summary

Hi,

After I turned on the csplitter, some search keys with 3 Chinese return no result, such as the key contains "输入法". Without csplitter, these keys return a lot of result. Is it anything to do with 'simple cjk' in the search setting or it has problem with 3 Chinese words. As document mention "使用时请关闭搜索设置里的“简单中日韩处理”. I turned off these one and reindex the site. If I turn on 'simple cjk', could the search result be better? Or what is the effect if I turn on both. Thanks.