If you are using JMP 18 or newer, look in the scripting index 'Python' category. There are many samples there. Specifically look a the jmp.DataTable object. It behaves as a Python list of columns, and each column behaves as a list of rows. The data table object itself is iterable and is direct in memory access to the data table.
See: Python Send(); and Python Get(); JSL functions ( read / write ) JSL variables to/from python.
In JMP 19 and beyond see jmp.globals and jmp.here dictionaries for accessing JSL global and here namespace variables from Python (read/write)
You don't need to go back and forth through CSV, but JSL can read/write CSV, and pandas in Python can directly read and write CSV if that's truly what you want.
Remember the jmp.DataTable access in Python is 0-based indexing while JSL operates on 1-based indexing.