JSon file

Probably what you need to do is play with the parameters of the JSON Reader. Depending of the structure of the JSON file the 'Auto' option for Schema Scan Mode wont always give you the best result.

You can switch the Schema Scan Mode to JSON Query and which will let you define your input feature types based on a given query. When adding a reader you can use the UI to drill down into the file which will build the query for you. Like in the screen shot here.

You can create as many feature types as you need each with a different query.

This is at least a good place to start if you're new to JSON. There's also a really good tutorial here about using FME to work with JOSN. I'd definitely recommend it because JSON is everywhere now and you can't do anything web related without knowing at least a little bit: https://community.safe.com/s/article/tutorial-getting-started-with-json