On their own, CSVs are a poor file format for survey data, because they don't contain any metadata (which includes subtle but important information about the data itself). Metadata generally includes information such as variable labels, value labels, whether the variables are sub-variables of a larger variable structure (such as a Categorical Array), and other related information about variables.
In the Crunch context, metadata description documents can include comprehensive information about the schema, the foundational information that forms the Variable Tree. This includes things like foldering and information that defines derived variables.
Using a CSV + json metadata document automates the setup of a dataset. It is far superior to using SPSS files, but requires investment in ensuring the metadata description document conforms to how Crunch reads a schema.
Creating the metadata document
In order to create a metadata description document (json) that Crunch can read, please review the full documentation here.
Here are two sample files, that illustrate on a few variables different variable types: