The SaveAs requires a script as it requires some objects to be passed that you really need a script to generate.
If you use the SaveAs method of the connector and change the extension, the file will still be in xlsx format and not converted to CSV.
The replace can be done in an automation, however it is best to do in a script. Pega Robotics has a limitation in the length of strings to pass in an automation. While this length is really long, it is not hard to imagine a large spreadsheet overtaking this.
In the attached solution, select an Excel file and it will get saved as a CSV and then have the comma replaced with a pipe. It will delete the CSV if it exists already.