Comment 49 for bug 391572

I don't see this as any different than having a numeric value such as 1.23456789 in a cell, formatted to
display as 1.235. When you edit it, you will see 1.23456789; to edit it as it was formatted, you may lose
data (in this case, 5 decimal places). Likewise, to pj's original comment so long ago, if you had formatted
the date as "QQ YYYY", and edited it according to the format, you would only be able to change the
quarter or the year, not the actual date in the cell. This is why editing and display should remain
separate.

That said, the problem seems to really be that the date editor, whether by double-click or in the entry
line, defaults to US date format, regardless of anything else. It seems that Issue 72229 really is the answer
- for all date cells, let the user pick the format that should be used for editing.