Probably, qa-include/util/string.php (around L709)
//@define('QA_PREG_INDEX_WORD_SEPARATOR', '[\n\r\t\ \!\"\\\'\(\)\*\+\,\.\/\:\;\<\=\>\?\[\\\\\]\^\`\{\|\}\~]');
@define('QA_PREG_INDEX_WORD_SEPARATOR', '[\n\r\t\ \!\"\\\'\(\)\*\,\.\/\:\;\<\=\>\?\[\\\\\]\^\`\{\|\}\~]');
//@define('QA_PREG_BLOCK_WORD_SEPARATOR', '[\n\r\t\ \!\"\\\'\(\)\+\,\.\/\:\;\<\=\>\?\[\\\\\]\^\`\{\|\}\~\$\&\-\_\#\%\@]');
@define('QA_PREG_BLOCK_WORD_SEPARATOR', '[\n\r\t\ \!\"\\\'\(\)\,\.\/\:\;\<\=\>\?\[\\\\\]\^\`\{\|\}\~\$\&\-\_\#\%\@]');
This hack will affect the whole system. Therefore, you need to apply this hack at your own risk. And, you need to be fully tested in the local environment.