![Файл AI Illustrator [обложка] .ai](https://i.stack.imgur.com/r1SMX.jpg)
Your file has been saved with an older (likely, much older) version of Adobe Illustrator. It is still the .ai file, yet with older, depreciated internal format.
Your modern Adobe Illustrator recognizes different formats which Adobe used over the years. It has a built-in converter for the older data formats and tt does convert the file internally when opening and loading it into workspace.
The [Converted] fragment in the internally assigned file name prevents you from overwriting the source file by mistake. Such an action would make the original file incompatible with the older Adobe Illustrator, by which the file was originally saved.
As for the editability... If you're not the author of the original file, it's hard to decide whether to put the blame on the conversion process or the original author, who may have made the text uneditable.
It is even possible that the file may have even been created and saved with a modern Adobe Illustrator, but with an older version of .ai file format enforced. Some editability may indeed be lost when using backward conversion.