Hey @aflick2486, Not sure if this helps, but here's a post on scripting a lookup with Python and the code has "import csv": https://answers.splunk.com/answers/145561/how-to-script-a-lookup-in-python.html
You have to get the .csv file to the search head first, see this question and this question. If you can't put the file to the search head, I would try to use the rest api to create a search with ... | outpulookup xxx, this might work for a small file, or have a universal forwarder which indexes the local file, and then a search which reads the index and writes the .csv file with an outputlookup
If you really want to maintain a lookup via the rest API the lookup has to be a kvstore lookup. CSV lookups cannot be directly modified. You can use python to read in the csv file but use the REST API to control a kvstore lookup.
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