I just came across this for the fdir function. I only copied the example code into AB and got these three errors. With double slash \\ it works fine for me.
Is this a mistake on my side or did this change over the years?
You should always use double backslash \\ for paths to files/directories in AFL.
I believe one backslash got removed in the code example of manual because of HTML. See your quote in my post. As you can see one backslash has disappeared also because of not being within code tags.
I do always use double backslash in functions I know. This one I used the first time and was playing around with the example.
And indeed I edited my post afterwards to three backslashes to see two in my post, this could indeed be it.