Do I need a new Test-type for each type of measurement file?
Not necessarily. Of course you could create a new Test-type for each and every new raw file type, but this will increase management- and configuration overhead.
If your measurements are for technical reasons of different file types, but
semantically belong to the same kind of Test (e.g., measuring a certain force)
semantically share the same set of meta information that is relevant to your data search & filtering later
it is recommended to group them under the same Test-type and use suitable meta field mappings and channel-name-unit mappings to unify access to the measurements.