Should I also change it on my mother's computer who doesn't speak English? We can also start distributing .bat files that change the system language along with our spreadsheets, for anyone who wants to open them. Maybe automate it with VBS, so it changes automatically when you open the spreadsheet. That's the solution.

Work computer, so I might not be able to do it.

Also, why shouldn’t I be able to choose which language I use in Excel when they’re clearly all available?

Why do software companies these days insist on treating me as though I can’t look after myself?