I would have a problem if a terminal app were to do something like this, but for GUI apps, it is expected for them to make stuff easier. And I feel like, if you were to use a slash in a file name, it would most probably be either an “or” slash or a fraction slash, so the substitution is fine in my books.
it’s close enough, i generally consider an “illegal” character a non typable character. Especially these alt characters that are visually hard to distinguish from others such as the forward slash for example, i believe this was the same character used for a handful of somewhat clever phishing scams.