The spreadsheet has a standard format, but using it means that they need to sit down at their computer rather than being able to do it on their phone (i.e. right after a meeting), and that they overwrite a previous instance of the spreadsheet, which leads to mismatches between accounts and activities, which requires me to go back to them and reconcile things wasting time for both of us.

It's possible to use the spreadsheet as basis for upload, but if I'm going to do that, I'll build my own front end too. I'm hoping to find something that will work rather than roll my own.