Useful, but are there any risks that accidentally including some dubious information might get your Google account suspended, including all its data? How do you make backups?
I don't understand the concern or why backups would be necessary. My understanding is that customers create their design as a spreadsheet (possibly using Google Sheets) and then simply pass that off to a designer to be converted into a Web design (presumably CSS/HTML?) I don't see why account suspension or backups are relevant here.
Google without any prior warning can just block your account for some reason, like violation of TOS. While it's seems to be unlikely for casual user, but must be considered.