For some reason someone back then thought it is a good idea to translate layer names inside the file format. I would assume this was tied to the language of kicad itself. Meaning it is not only dependent on the kicad version that was used to create the file but possibly also the language selected for it while creating the file.
but I had the same problem with V4: I installed V5 thinking to solve…
v3 to v4 the same problem
v3 to v5 the same problem
That is what i was meaning with the post you answered to. KiCad 5 and KiCad 4 need the same process to open a v3 project (created in a different language than english).
Did you try the process described by the answer of @Seth_h?
Did this make problems when a KiCad 3 Polish file was read by a KiCad 3 Spanish PC?
What a bizarre thing to do.
ok… having the projects in my old PC with the old version of KiCAD : I could set the old KiCAD in English language and save again and solve?
argghhhhhh more confused! yes it’s ok!
The layers had layer numbers back then. Which leaves me to assume that kicad back then did not really use the layer name for anything other than showing it in the layer lists inside of kicad.
I then wonder why the system to transfer such an old file forward relies on the layer name.
I changed the language and now not even open in the old KiCAD… the same problem…
It’s simple, the old version of Kicad
named the technical layers in the local languages (French, Italian, English, etc …) The person who made the script in Perl had a Kicad file made with the Italian version. Which corresponded with your file. So, you are lucky. For other languages, for example in French, you will need to modify the Perl file.
Check who you answered. I am not the owner of any such old files 
so you opened my file using the Perl script… right?
Yes, that’s what I did. You must install Perl. But made a backup, it’s more careful.
Sorry for the inconvenience.
the script instead where I find it? I am installing the Perl…
The script is here
Sorry I had not seen that I had to expand the post…
The script as I put it in the project folder KiCAD? I Go from the DOS in the project folder KiCad that interests me and launch it there?
You can find the link with the “search topic” in the forum
Italian Convert version older than Ver 4 top right of the page.
Or click directly on the sentence in blue in my
last message.
I thank all for the informations and the help you have given me 
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