Current macOS Finder let's you name files with a slash in them, rendered as a : in the terminal.
I think that the slash might be the rendering though? If you
$ touch "foo:bar"
In the Terminal, then Finder renders it as foo/bar.So who is lying, how is it stored in the directory entry in APFS itself?
Isn't that just what the original article that we all commented on described? I don't understand what you are trying to add to the conversation here.