Check this:
Yes, it replied false.
Another one does too.
Learn JSON
Make a Dictionary will return a Dictionary.
But you connect it with File.SaveFile, the text socket need a String, AI will change Dictionary to String/JSON.
When you read from the file, you will get a String, you need to use Web.JsonTextDecode to convert String/JSON to dictionary.
Why not use a csv for read write and convert csv to dictionary when needed ?