I am in the same boat as Gizmo.
I have always allowed the upgrade script to upload the language files.
I think I did edit them once in version 7.0 but it was due to a error in the files and the next release corrected it.
So I opted to just overwrite it during the upgrade later on.
So bottom line is I don't know
But you could just backup that folder before you upgrade for just in case.
But better yet is a full backup before you upgrade(suggested)
Personally if their is a new key field or updates to the key field contents I can't figure out how the upgrade script would really know the difference. Unless it will report each and every field contents. so you can choose field one is okay to overwrite and field two is not
As I recall it just shows if the files are different.
Been to long since upgrading the last time.
