Are you wanting to write this yourself? If so what languages are writing in/learning?
If you’re familiar with any scripting language and making requests to an API this would be fairly simple to write.
You would need to parse the CSV, use the Airtable API for listing and and updating records and then iterate and evaluate each line of your CSV file against records in your Airtable.
For example. In python there is a preinstalled CSV module and you can use the requests module for API calls. In Javascript you can use a node module like csv-parser and make requests using the airtable module.