I'm not sure I understand the issue, so I will try to clarify few things:
1. In case no parser was applied, the entire syslog message will be parsed into "default_device_message" and the product/blade will be called "Syslog"
2. Using the Eventia Log Parser, you can configure your parser by copying a log example and map the fields to Check Point fields or to your own fields (notice that in case you are using your own fields, they will not be indexed). You can also configure what the product name will be called.
3. Once you apply those changes (using the Eventia scripts from the SK), the log server will parse the data and the fields will be populated