To clarify, the template itself does not need editing. It's only the way the template is entered on the profile that needs to change.
Personally, I don't mind using flags that weren't in use at the time, as long as they represent a place that existed at the time. Eg. I would normally use the current Canadian flag to represent Canada all the way back to Confederation in 1867 (but not before, because Canada didn't exist before that), even though that flag wasn't adopted until 1965. And we use the Acadian flag for the Acadians, even though that flag is a modern invention that the original Acadians would never have seen.