You can use...Embedded Python! You just need a business service EnsLib.File.PassthroughService to get the the json file and send it into a BP with a ClassMethod to get all the lines, here you can see an example:

https://www.geeksforgeeks.org/read-a-file-line-by-line-in-python/

You can save the object directly from the Embedded Python method or return a list of strings and map it into an Objectscript object.

About the CSPSystem, I had some troubles to connect when I used the superuser from VSC and the webgateway had the CSPSystem user configured, It solved when I changed the user to superuser.

Probably you are right and is not necessary to change the CSPSystem (my current configuration it's using CSPSystem and works fine) it just was pure chance.