What I'm experiencing is when the term 'NOT' is within the string(s) of columns we are trying to join, I'm getting back 'OperationalError: malformed MATCH expression' . My feeling is because there is a SQL dependency for reserved words, example below ought to show error.
The below code snipped ought to reproduce error.
x1=pd.DataFrame(['xyz NOT', 'YES', '425255'], columns=['X'])
x2=pd.DataFrame(['NOT', 'OK', '42525511'], columns=['X'])
fuzzy_left_join(x1,x2, left_on='X', right_on='X')