So before thinking of modifying things in FSCrawler, you need to find the right analyzers, mapping for your use case.
The easiest way is to start with some sample minimalist documents (just one field) and play around with the API.
Once you have a full script which reproduces the problem as described in About the Elasticsearch category, share it here. It will help to better understand what you are doing. Please, try to keep the example as simple as possible.
A full reproduction script will help readers to understand, reproduce and if needed fix your problem. It will also most likely help to get a faster answer.