Bug - language vs stage name

If you change the original language of a project to another language, the scene is auto-renamed with a translation to the new language.

if i change to french:

This is sorta like when you rename a variable but all of the old instances aren't updated so you have to track down each one and replace it.

Unless you use the rename all option

the rename all option is bugged, though, and doesn't always work for global vars.

If you rename the stage and after you change the language, the stage is renamed in the same way.

Wait a minute. I thought that renamed all the variables.

Another subject about the name of the stage:
I dont know the utility to rename the stage in a project. There is only one stage in a project (now in v7, there is only one stage in a scene):

Why i need to rename the stage ?

Maybe I can't see something ?

I only really use it for script vars, so, I don't have much experience with rename all global/sprite local vars.