generally, it is not a good idea to mess with terminal rules in the very beginning. You may think that "find" will be interpreted as a keyword, but due to your SEARCH_WORD definition it will be a SEARCH_WORD-token.
The very first step when reading a model is lexing. The document will be chopped into tokens and the lexer will make them as long as possible. "find" is a possible token (keyword) but "find " is longer and fits the SEARCH_WORD definition as that swallows up EVERYTHING that is not a special character.