Nor do I know anyone in the UK who uses
Jacques for
Jack or vice-versa. Perhaps they do in Northern mainland Europe?
The connection between
Jack and
John is still well known in the UK (although it is not as well understood in the States).
Some books claim that
Alice means 'truth' - it doesn't. Just because books claim it and people repeat it, doesn't mean there's a connection. It means there is an error.
I would differentiate here; perhaps you would not. Certainly, producing a PhD. has sharpened my perspective on this :)