I moved away from Microsoft excel and made the planner exclusively Google Sheets. For the sole reason, free, many people I fly with have Google accounts and the iterative calculations functioned better with error handling. Sign in with Google, make a copy and enjoy the planners full potential. I regularly tune and update this to meet the needs of users and simplicity. The website is really for demo, but works as advertised in the standalone too. I would like to see the new Google Sites utilize a wider embed area. With a wide sheet, it causes irritating scroll bars.
The native locale is US. The coordinates and some other cells will be confused by commas and periods in the wrong place.
Sorry you are having a bad standalone experience, but the best way to utilize this is with Google Sheets and to do that you will need a Google account.
Thanks for the great feedback and check out the new updates regularly.