Does anyone have any more information about why Netsuite would error out if you clicked into an empty cell of a CSV? Is there a way around this so that I don't have to worry about either deleting the empty cells or being extremely careful not to click on any cells that are off to the side?

Presuming you're using Excel to create the CSV files. This is to do with Excel, which has a concept of "last used cell". Basically by clicking into an empty cell that is past where your actual data is, Excel sets that to be the new 'last used cell'. When you then save the sheet as a CSV, Excel will append empty rows/columns to reach what it thinks is the complete spreadsheet

I didn't think it was clicking into an empty cell, I always thought it was having data in there and then deleting it. Either way, as a general rule, I'll usually delete (not clear data) all blank columns and all blank roles rows before saving as CSV. Unless I know the source of the Excel file and there was not data in any of the blank rows at one time.