I'm afraid I can't explain this; perhaps someone else can. If it
bothers you, consider temporarily setting LC_ALL=C (or C.UTF-8)
while you sort.
Don't waste any time on it. I've run into this 'locale' stuff in
the past and as I said I think it's a can of worms. You might think
that all English dictionaries would use the same lexicography, but
... In every practical way '(n)' gives me just what I want. Oh, but
it was good to shake out the idea that 'numeric' or 'version' were
the issue. As you show, even dictionary sort seems to go strange.
Let it be.