Using Chrome 119, I see

  SyntaxError: Invalid regular expression: /^(?<year>\d{4})(\-)(?<month>\d{1,2})(\-)(?<year>\d{1,2})T(?<hour>\d{1,2})\:(?<minute>\d{1,2})\:(?<second>\d{1,2})(Z?)$/i: Duplicate capture group name

This happens whenever I insert text to any cell. I just tried inserting "TEST" to a cell on the first sheet, then pushed the Enter key. It also happens when I use arrow keys to move away from a cell I am editing.

Ah. Yes i figured out the issue. Could you share your current location? Are you in the US or Japan? We create a date pattern matching expression based on your current locale.

Yeah, I am currently in the US, using a MacBook with Japanese locale set.

Awesome. I have fixed this issue for you.

Cool, real-time debugging and deploying a fix in minutes. We've come a long way since the days of shrinkwrapped spreadsheet software sold in a store.

Thanks for the feedback. I will look into this.

Does the error go away if you just refresh the demo?

Yeah, refreshing the page makes everything work again. I can see changes to the spreadsheet in real-time and I am capable of resizing cells, changing fonts, etc. The only problem is with editing the contents of a cell.